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Butler L, Karabayir I, Kitzman DW, Alonso A, Tison GH, Chen LY, Chang PP, Clifford G, Soliman EZ, Akbilgic O. A generalizable electrocardiogram-based artificial intelligence model for 10-year heart failure risk prediction. CARDIOVASCULAR DIGITAL HEALTH JOURNAL 2023; 4:183-190. [PMID: 38222101 PMCID: PMC10787146 DOI: 10.1016/j.cvdhj.2023.11.003] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2024] Open
Abstract
Background Heart failure (HF) is a progressive condition with high global incidence. HF has two main subtypes: HF with preserved ejection fraction (HFpEF) and HF with reduced ejection fraction (HFrEF). There is an inherent need for simple yet effective electrocardiogram (ECG)-based artificial intelligence (AI; ECG-AI) models that can predict HF risk early to allow for risk modification. Objective The main objectives were to validate HF risk prediction models using Multi-Ethnic Study of Atherosclerosis (MESA) data and assess performance on HFpEF and HFrEF classification. Methods There were six models in comparision derived using ARIC data. 1) The ECG-AI model predicting HF risk was developed using raw 12-lead ECGs with a convolutional neural network. The clinical models from 2) ARIC (ARIC-HF) and 3) Framingham Heart Study (FHS-HF) used 9 and 8 variables, respectively. 4) Cox proportional hazards (CPH) model developed using the clinical risk factors in ARIC-HF or FHS-HF. 5) CPH model using the outcome of ECG-AI and the clinical risk factors used in CPH model (ECG-AI-Cox) and 6) A Light Gradient Boosting Machine model using 288 ECG Characteristics (ECG-Chars). All the models were validated on MESA. The performances of these models were evaluated using the area under the receiver operating characteristic curve (AUC) and compared using the DeLong test. Results ECG-AI, ECG-Chars, and ECG-AI-Cox resulted in validation AUCs of 0.77, 0.73, and 0.84, respectively. ARIC-HF and FHS-HF yielded AUCs of 0.76 and 0.74, respectively, and CPH resulted in AUC = 0.78. ECG-AI-Cox outperformed all other models. ECG-AI-Cox provided an AUC of 0.85 for HFrEF and 0.83 for HFpEF. Conclusion ECG-AI using ECGs provides better-validated predictions when compared to HF risk calculators, and the ECG feature model and also works well with HFpEF and HFrEF classification.
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Affiliation(s)
- Liam Butler
- Epidemiological Cardiology Research Center, Section on Cardiovascular Medicine, Department of Medicine, Wake Forest School of Medicine, Winston-Salem, North Carolina
| | - Ibrahim Karabayir
- Epidemiological Cardiology Research Center, Section on Cardiovascular Medicine, Department of Medicine, Wake Forest School of Medicine, Winston-Salem, North Carolina
| | - Dalane W. Kitzman
- Epidemiological Cardiology Research Center, Section on Cardiovascular Medicine, Department of Medicine, Wake Forest School of Medicine, Winston-Salem, North Carolina
| | - Alvaro Alonso
- Rollins School of Public Health, Emory University, Atlanta, Georgia
| | - Geoffrey H. Tison
- Division of Cardiology, University of California, San Francisco, California
| | - Lin Yee Chen
- Lillehei Heart Institute and the Department of Medicine (Cardiovascular Division), University of Minnesota Medical School, Minneapolis, Minnesota
| | - Patricia P. Chang
- Department of Medicine (Division of Cardiology), University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
| | - Gari Clifford
- Department of Biomedical Informatics, Emory School of Medicine, Emory University, Atlanta, Georgia
- Wallace H. Coulter Department of Biomedical Engineering, College of Engineering, Georgia Institute of Technology, Atlanta, Georgia
| | - Elsayed Z. Soliman
- Epidemiological Cardiology Research Center, Section on Cardiovascular Medicine, Department of Medicine, Wake Forest School of Medicine, Winston-Salem, North Carolina
| | - Oguz Akbilgic
- Epidemiological Cardiology Research Center, Section on Cardiovascular Medicine, Department of Medicine, Wake Forest School of Medicine, Winston-Salem, North Carolina
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You T, Xie Y, Luo C, Zhang K, Zhang H. Mechanistic insights into spontaneous transition from cellular alternans to ventricular fibrillation. Physiol Rep 2023; 11:e15619. [PMID: 36863774 PMCID: PMC9981424 DOI: 10.14814/phy2.15619] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2023] [Revised: 02/04/2023] [Accepted: 02/05/2023] [Indexed: 03/04/2023] Open
Abstract
T-wave alternans (TWA) has been used for predicting the risk of malignant cardiac arrhythmias and sudden cardiac death (SCD) in multiple clinical settings; however, possible mechanism(s) underlying the spontaneous transition from cellular alternans reflected by TWA to arrhythmias in impaired repolarization remains unclear. The healthy guinea pig ventricular myocytes under E-4031 blocking IKr (0.1 μM, N = 12; 0.3 μM, N = 10; 1 μM, N = 10) were evaluated using whole-cell patch-clamp. The electrophysiological properties of isolated perfused guinea pig hearts under E-4031 (0.1 μM, N = 5; 0.3 μM, N = 5; 1 μM, N = 5) were evaluated using dual- optical mapping. The amplitude/threshold/restitution curves of action potential duration (APD) alternans and potential mechanism(s) underlying the spontaneous transition of cellular alternans to ventricular fibrillation (VF) were examined. There were longer APD80 and increased amplitude and threshold of APD alternans in E-4031 group compared with baseline group, which was reflected by more pronounced arrhythmogenesis at the tissue level, and were associated with steep restitution curves of the APD and the conduction velocity (CV). Conduction of AP alternans augmented tissue's functional spatiotemporal heterogeneity of regional AP/Ca alternans, as well as the AP/Ca dispersion, leading to localized uni-directional conduction block that spontaneous facilitated the formation of reentrant excitation waves without the need for additional premature stimulus. Our results provide a possible mechanism for the spontaneous transition from cardiac electrical alternans in cellular action potentials and intercellular conduction without the involvement of premature excitations, and explain the increased susceptibility to ventricular arrhythmias in impaired repolarization. In this study, we implemented voltage-clamp and dual-optical mapping approaches to investigate the underlying mechanism(s) for the arrhythmogenesis of cardiac alternans in the guinea pig heart at cellular and tissue levels. Our results demonstrated a spontaneous development of reentry from cellular alternans, arising from a combined actions of restitution properties of action potential duration, conduction velocity of excitation wave and interplay between alternants of action potential and the intracellular Ca handling. We believe this study provides new insights into underlying the mechanism, by which cellular cardiac alternans spontaneously evolves into cardiac arrhythmias.
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Affiliation(s)
- Tingting You
- Key Laboratory of Medical Electrophysiology, Ministry of Education and Medical Electrophysiological Key Laboratory of Sichuan Province, (Collaborative Innovation Center for Prevention of Cardiovascular Diseases)Institute of Cardiovascular Research, Southwest Medical UniversityLuzhouChina
- Department of NeurosurgeryXinqiao Hospital, Army Medical UniversityChongqingChina
| | - Yulong Xie
- Key Laboratory of Medical Electrophysiology, Ministry of Education and Medical Electrophysiological Key Laboratory of Sichuan Province, (Collaborative Innovation Center for Prevention of Cardiovascular Diseases)Institute of Cardiovascular Research, Southwest Medical UniversityLuzhouChina
| | - Cunjin Luo
- School of Computer Science and Electronic EngineeringUniversity of EssexColchesterUK
| | - Kevin Zhang
- School of MedicineImperial College of LondonLondonUK
| | - Henggui Zhang
- Key Laboratory of Medical Electrophysiology, Ministry of Education and Medical Electrophysiological Key Laboratory of Sichuan Province, (Collaborative Innovation Center for Prevention of Cardiovascular Diseases)Institute of Cardiovascular Research, Southwest Medical UniversityLuzhouChina
- Department of Physics and AstronomyUniversity of ManchesterManchesterUK
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You T, Luo C, Zhang K, Zhang H. Electrophysiological Mechanisms Underlying T-Wave Alternans and Their Role in Arrhythmogenesis. Front Physiol 2021; 12:614946. [PMID: 33746768 PMCID: PMC7969788 DOI: 10.3389/fphys.2021.614946] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2020] [Accepted: 02/10/2021] [Indexed: 12/18/2022] Open
Abstract
T-wave alternans (TWA) reflects every-other-beat alterations in the morphology of the electrocardiogram ST segment or T wave in the setting of a constant heart rate, hence, in the absence of heart rate variability. It is believed to be associated with the dispersion of repolarization and has been used as a non-invasive marker for predicting the risk of malignant cardiac arrhythmias and sudden cardiac death as numerous studies have shown. This review aims to provide up-to-date review on both experimental and simulation studies in elucidating possible mechanisms underlying the genesis of TWA at the cellular level, as well as the genesis of spatially concordant/discordant alternans at the tissue level, and their transition to cardiac arrhythmia. Recent progress and future perspectives in antiarrhythmic therapies associated with TWA are also discussed.
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Affiliation(s)
- Tingting You
- Key Lab of Medical Electrophysiology, Ministry of Education, Institute of Cardiovascular Research, Southwest Medical University, Luzhou, China
| | - Cunjin Luo
- School of Computer Science and Electronic Engineering, University of Essex, Colchester, United Kingdom
| | - Kevin Zhang
- School of Medicine, Imperial College of London, London, United Kingdom
| | - Henggui Zhang
- Key Lab of Medical Electrophysiology, Ministry of Education, Institute of Cardiovascular Research, Southwest Medical University, Luzhou, China.,Department of Physics and Astronomy, University of Manchester, Manchester, United Kingdom
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Alaei S, Wang S, Anaya P, Patwardhan A. Co-occurrence and phase relationship between alternans of the R wave amplitude (RWAA) and of the T wave (TWA) in ECGs. Comput Biol Med 2020; 121:103785. [PMID: 32568673 DOI: 10.1016/j.compbiomed.2020.103785] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2019] [Revised: 04/22/2020] [Accepted: 04/23/2020] [Indexed: 11/15/2022]
Abstract
Alternans of the T wave in ECG (TWA) has high negative but poor positive predictive value in the prediction of ventricular arrhythmia. Alternans of repolarization duration, i.e. of action potential duration (APD), causes TWA. Prior studies from our group showed that alternans of the maximum rate of depolarization also occurs when APD alternans occurs and the relationship between these two has the potential to affect formation of spatial discord, which may be more arrhythmogenic. Therefore, exploration of the co-occurrence of the alternans of depolarization and repolarization has the potential to improve the prediction. In the present study, we used a mathematical model to show that depolarization alternans appears as alternating amplitude of the R wave in the ECG. We also investigated the link between changes in R wave amplitude and TWA. Results from clinical grade ECGs available in the PhysioNet database show that amplitude of the R wave can change as predicted by our experimental results and the mathematical model. Using TWA as the marker of repolarization alternans and R wave amplitude alternans (RWAA) as the marker of depolarization alternans, we investigated the phase relation between them and observed that, similar to previous results from animals, the phase relation between the two can spontaneously change. That is, alternans of depolarization does co-occur with TWA and the phase relationship between the two is not invariant. These results support further investigation of the use of RWAA as a complementary method to TWA to improve positive predictive value for prediction of ventricular arrhythmia.
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Affiliation(s)
- Sahar Alaei
- F. Joseph Halcomb III, M.D. Department of Biomedical Engineering, University of Kentucky, United States
| | - Siqi Wang
- F. Joseph Halcomb III, M.D. Department of Biomedical Engineering, University of Kentucky, United States
| | - Paul Anaya
- Division of Cardiovascular Medicine, Department of Internal Medicine, Gill Heart Institute, University of Kentucky, United States
| | - Abhijit Patwardhan
- F. Joseph Halcomb III, M.D. Department of Biomedical Engineering, University of Kentucky, United States.
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Spicher N, Kukuk M. Delineation of Electrocardiograms Using Multiscale Parameter Estimation. IEEE J Biomed Health Inform 2020; 24:2216-2229. [PMID: 32012030 DOI: 10.1109/jbhi.2019.2963786] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The continuing interest in unobtrusive electrocardiography requires the development of algorithms, compensating for an increased number of artifacts. In previous work, we proposed a framework for robust parameter estimation of signals following a piecewise Gaussian derivative model, well suited for describing all waves of a heartbeat. The framework is based on a numeric and analytic representation of applying the Wavelet Transform at arbitrary scale to the input model. For robustly estimating model parameters, it processes lines of zero-crossings in scale-space, showing high accuracy for various noise models in synthetic signals. An initial evaluation with electrocardiography signals revealed that our basic classifier for identifying the correct lines often fails, leading to false parameter estimates. In this work, we propose a general delineation method based on a solid mathematical framework that treats each heartbeat, wave and fiducial point in the same way, tailored only by intuitive parameters and not relying on any heuristically found decision rules. The steps include a novel line classifier based on pre-filtering using domain knowledge, followed by an exhaustive search among all possible combinations of zero-crossing lines and an error-measure quantifying their agreement with the model. The combination with highest agreement is processed by the parameter estimation framework, customized to the computation of all nine fiducial points. Evaluation using the expert-annotated QT database, shows high sensitivity (P: 99.91%, QRS: 99.92%, T: 99.89%) and mean errors below 1 ms for all onset and offset fiducial points. The proposed combination of line classification and parameter estimation is well suited for delineating electrocardiograms.
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Abstract
Purpose of Review Non-ischaemic dilated cardiomyopathy (DCM) occurs in 1 in 2500 individuals in the general population and is associated with considerable morbidity and mortality. Studies involving large numbers of unselected DCM patients have led to consensus guidelines recommending implantable cardioverter-defibrillator (ICD) implantation for protection against sudden cardiac death (SCD) in those with LVEF ≤35%. The purpose of this article is to review the literature for other potential markers including serological, electrocardiographic, echocardiographic, cardiac magnetic resonance, ambulatory ECG and genetic data, to highlight other potential markers that may optimise risk stratification for SCD in this cohort and thereby allow a more personalized approach to ICD-implantation. Recent Findings Recent studies including the Danish study to assess the efficacy of ICDs in patients with non-ischemic systolic heart failure on mortality (DANISH) trial have questioned the benefits of ICD implantation in this group of patients with no changes in all-cause mortality. Recent pooled cohorts of patients with genetic DCM and in particular in those with Lamin A/C (LMNA) mutations have identified patients at increased risk of SCD and allowed the creation of algorithms to prognosticate SCD risk in mutation carriers. Furthermore, genetic testing has identified other DCM-causing genes including filamin C (FLNC) and RBM20 which may be associated with higher rates of ventricular arrhythmia. Summary To date, risk-stratification for SCD has been hampered by the utilisation of heterogenous subsets of idiopathic DCM patients and by use of static risk models where predictions are based on a single time point with a lack of consideration of disease progression. The current focus of personalised risk-stratification for SCD is shifting towards better characterisation of underlying DCM aetiology and the development of multi-parametric risk-stratification models that incorporate time-dependent disease characteristics and novel biomarkers.
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Microvolt T-wave alternans at the end of surgery is associated with postoperative mortality in cardiac surgery patients. Sci Rep 2019; 9:17351. [PMID: 31758018 PMCID: PMC6874567 DOI: 10.1038/s41598-019-53760-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2018] [Accepted: 11/05/2019] [Indexed: 11/08/2022] Open
Abstract
Microvolt T-wave alternans (MTWA), which reflects electrical dispersion of repolarization, is known to be associated with arrhythmia or sudden cardiac death in high risk patients. In this study we investigated the relationship between MTWA and postoperative mortality in 330 cardiac surgery patients. Electrocardiogram, official national data and electric chart were analysed to provide in-hospital and mid-term outcome. MTWA at the end of surgery was significantly associated with in-hospital mortality in both univariate analysis (OR = 27.378, 95% CI 5.616-133.466, p < 0.001) and multivariate analysis (OR = 59.225, 95% CI 6.061-578.748, p < 0.001). Cox proportional hazards model revealed MTWA at the end of surgery was independently associated with mid-term mortality (HR = 4.337, 95% CI 1.594-11.795). The area under the curve of the model evaluating MTWA at the end of surgery was 0.764 (95% CI, 0.715-0.809) and it increased to 0.929 (95% CI, 0.896-0.954) when combined with the EuroSCORE II. MTWA positive at the end of surgery had a 60-fold increase in in-hospital mortality and a 4-fold increase in mid-term mortality. Moreover, MTWA at the end of surgery could predict in-hospital mortality and this predictability is more robust when combined with the EuroSCORE II.
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Fukaya H, Plummer BN, Piktel JS, Wan X, Rosenbaum DS, Laurita KR, Wilson LD. Arrhythmogenic cardiac alternans in heart failure is suppressed by late sodium current blockade by ranolazine. Heart Rhythm 2019; 16:281-289. [PMID: 30193854 DOI: 10.1016/j.hrthm.2018.08.033] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/29/2017] [Indexed: 12/19/2022]
Abstract
BACKGROUND Cardiac alternans is promoted by heart failure (HF)-induced calcium (Ca2+) cycling abnormalities. Late sodium current (INa,L) is enhanced in HF and promotes Ca2+ overload; however, mechanisms underlying an antiarrhythmic effect of INa,L blockade in HF remain unclear. OBJECTIVE The purpose of this study was to determine whether ranolazine suppresses cardiac alternans in HF by normalizing Ca2+ cycling. METHODS Transmural dual optical mapping of Ca2+ transients and action potentials was performed in wedge preparations from 8 HF and 8 control (normal) dogs. Susceptibility to action potential duration alternans (APD-ALT) and Ca2+ transient alternans (Ca-ALT) was compared at baseline and with ranolazine (5-10 μM). RESULTS HF increased APD- and Ca-ALT compared to normal (both P <.05), and ranolazine suppressed APD- and Ca-ALT in both groups (P <.05). The incidence of spatially discordant alternans (DIS-ALT) was increased by HF (8/8) compared to normal (4/8; P <.05), and ranolazine decreased DIS-ALT in HF (4/8; P <.05).Not only did ranolazine mitigate HF-induced Ca2+ overload, it also attenuated APD-ALT to Ca-ALT gain (amount of APD-ALT produced by Ca-ALT). In HF, APD-ALT to Ca-ALT gain was significantly increased (0.55 ± 0.02) compared to normal (0.44 ± 0.02; P <.05) and was normalized by ranolazine (0.36 ± 0.05; P <.05), representing a complementary mechanism by which INa,L blockade suppressed cardiac alternans. CONCLUSION Ranolazine attenuated arrhythmogenic cardiac alternans in HF, both by suppressing Ca-ALT and decreasing the coupling gain of APD-ALT to Ca-ALT. Blockade of INa,L may reverse impaired Ca2+ cycling to mitigate cardiac alternans, representing a mechanism underlying the antiarrhythmic benefit of INa,L blockade in HF.
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Affiliation(s)
- Hidehira Fukaya
- Heart and Vascular Research Center, Case Western Reserve University, Cleveland, Ohio; Department of Cardiovascular Medicine, Kitasato University School of Medicine, Sagamihara, Kanagawa, Japan
| | - Bradley N Plummer
- Heart and Vascular Research Center, Case Western Reserve University, Cleveland, Ohio
| | - Joseph S Piktel
- Heart and Vascular Research Center, Case Western Reserve University, Cleveland, Ohio; Department of Emergency Medicine, MetroHealth Campus, Case Western Reserve University, Cleveland, Ohio
| | - Xiaoping Wan
- Heart and Vascular Research Center, Case Western Reserve University, Cleveland, Ohio
| | - David S Rosenbaum
- Heart and Vascular Research Center, Case Western Reserve University, Cleveland, Ohio
| | - Kenneth R Laurita
- Heart and Vascular Research Center, Case Western Reserve University, Cleveland, Ohio
| | - Lance D Wilson
- Heart and Vascular Research Center, Case Western Reserve University, Cleveland, Ohio; Department of Emergency Medicine, MetroHealth Campus, Case Western Reserve University, Cleveland, Ohio.
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Hashimoto K, Kasamaki Y, Soma M, Takase B. Diurnal variation of frequency domain T-wave alternans on 24-hour ambulatory electrocardiogram in subjects without heart disease: Significant effect of autonomic nervous activity of the heart. Ann Noninvasive Electrocardiol 2018; 24:e12620. [PMID: 30403436 DOI: 10.1111/anec.12620] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/08/2018] [Revised: 09/09/2018] [Accepted: 09/18/2018] [Indexed: 11/30/2022] Open
Abstract
BACKGROUND T-wave alternans (TWA) is a risk stratification predictor for sudden cardiac death. However, little is known about the diurnal variation of TWA. Whether TWA are affected by heart rate (HR) or cardiac autonomic nervous activity in the subjects without significant structural heart disease in daily life is not fully understood. Thus, this study was aimed to clarify these issues. METHODS Frequency domain (FD)-TWA analysis was conducted in 47 subjects without significant structural heart disease using 24-hr ambulatory electrocardiogram (AECG). Measurement of heart rate variability (HRV) was performed in order to evaluate the autonomic activity of the heart. The maximum FD-TWA value in each period was measured four times per day (A, 00:00-6:00 hr; B, 06:00-12:00 hr; C, 12:00-18:00 hr; D, 18:00-24:00 hr). Correlations between FD-TWA and either HR or HRV parameters (LF/HF, LFnu, HFnu, SDNN, CVNN, pNN50) were analyzed in each period (A-D). RESULTS There was diurnal variation of FD-TWA (median, inter-quartile range [IQR]: A, 8.2 [6.5, 10.6] μV; B, 10.1 [8.4, 15.0] μV; C, 17.6 [12.3, 25.0] μV: D, 11.9 [9.1, 19.9] μV; p < 0.0001). Maximum FD-TWA had positive correlations with HR and LF/HF (HR, r = 0.496, p < 0.0001; LF/HF, r = 0.414, p = 0.004), while FD-TWA had a negative correlation with HFnu (r = -0.291, p = 0.048). On multiple linear regression analysis, HR had an independent effect on log FD-TWA amplitude (β = 0.461, p = 0.001). CONCLUSIONS FD-TWA has marked diurnal variation in the daily life of the subjects without significant structural heart disease. This variation could be more strongly affected by HR than the HRV indices.
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Affiliation(s)
- Kenichi Hashimoto
- Department of Intensive Care Medicine, National Defense Medical College, Saitama, Japan
| | - Yuji Kasamaki
- Department of General Medicine, Kanazawa Medical University Himi Municipal Hospital, Kanazawa, Japan
| | - Masayoshi Soma
- Division of General Medicine, Department of Medicine, Nihon University School of Medicine, Tokyo, Japan
| | - Bonpei Takase
- Department of Intensive Care Medicine, National Defense Medical College, Saitama, Japan
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Janusek D, Svehlikova J, Zelinka J, Weigl W, Zaczek R, Opolski G, Tysler M, Maniewski R. The roles of mid-myocardial and epicardial cells in T-wave alternans development: a simulation study. Biomed Eng Online 2018; 17:57. [PMID: 29739399 PMCID: PMC5941457 DOI: 10.1186/s12938-018-0492-6] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2017] [Accepted: 04/28/2018] [Indexed: 01/31/2023] Open
Abstract
Background The occurrence of T-wave alternans in electrocardiographic signals was recently linked to susceptibility to ventricular arrhythmias and sudden cardiac death. Thus, by detecting and comprehending the origins of T-wave alternans, it might be possible to prevent such events. Results Here, we simulated T-wave alternans in a computer-generated human heart model by modulating the action potential duration and amplitude during the first part of the repolarization phase. We hypothesized that changes in the intracardiac alternans patterns of action potential properties would differentially influence T-wave alternans measurements at the body surface. Specifically, changes were simulated globally in the whole left and right ventricles to simulate concordant T-wave alternans, and locally in selected regions to simulate discordant and regional discordant, hereinafter referred to as “regional”, T-wave alternans. Body surface potential maps and 12-lead electrocardiographic signals were then computed. In depth discrimination, the influence of epicardial layers on T-wave alternans development was significantly higher than that of mid-myocardial cells. Meanwhile, spatial discrimination revealed that discordant and regional action potential property changes had a higher influence on T-wave alternans amplitude than concordant changes. Notably, varying T-wave alternans sources yielded distinct body surface potential map patterns for T-wave alternans amplitude, which can be used for location of regions within hearts exhibiting impaired repolarization. The highest ability for T-wave alternans detection was achieved in lead V1. Ultimately, we proposed new parameters Vector Magnitude Alternans and Vector Angle Alternans, with higher ability for T-wave alternans detection when using multi-lead electrocardiographic signals processing than for single leads. Finally, QT alternans was found to be associated with the process of T-wave alternans generation. Conclusions The distributions of the body surface T-wave alternans amplitude have been shown to have unique patterns depending on the type of alternans (concordant, discordant or regional) and the location of the disturbance in the heart. The influence of epicardial cells on T-wave alternans development is significantly higher than that of mid-myocardial cells, among which the sub-endocardial layer exerted the highest influence. QT interval alternans is identified as a phenomenon that correlate with T-wave alternans.
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Affiliation(s)
- D Janusek
- Nalecz Institute of Biocybernetics and Biomedical Engineering, Polish Academy of Sciences, 4 Ks Trojdena Str., 02-109, Warsaw, Poland.
| | - J Svehlikova
- Institute of Measurement Science, Slovak Academy of Sciences, Bratislava, Slovakia
| | - J Zelinka
- Institute of Measurement Science, Slovak Academy of Sciences, Bratislava, Slovakia
| | - W Weigl
- Department of Surgical Sciences/Anaesthesiology and Intensive Care, Uppsala University, Akademiska Hospital, Uppsala, Sweden
| | - R Zaczek
- Department of Cardiology, Central Clinical Hospital of Medical University of Warsaw, Warsaw, Poland
| | - G Opolski
- Department of Cardiology, Central Clinical Hospital of Medical University of Warsaw, Warsaw, Poland
| | - M Tysler
- Institute of Measurement Science, Slovak Academy of Sciences, Bratislava, Slovakia
| | - R Maniewski
- Nalecz Institute of Biocybernetics and Biomedical Engineering, Polish Academy of Sciences, 4 Ks Trojdena Str., 02-109, Warsaw, Poland
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Ayesta A, Martínez-Sellés H, Bayés de Luna A, Martínez-Sellés M. Prediction of sudden death in elderly patients with heart failure. J Geriatr Cardiol 2018; 15:185-192. [PMID: 29662512 PMCID: PMC5895958 DOI: 10.11909/j.issn.1671-5411.2018.02.008] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2018] [Revised: 02/25/2018] [Accepted: 02/27/2018] [Indexed: 02/06/2023] Open
Abstract
Most heart failure (HF) related mortality is due to sudden cardiac death (SCD) and worsening HF, particularly in the case of reduced ejection fraction. Predicting and preventing SCD is an important goal but most works include no or few patients with advanced age, and the prevention of SCD in elderly patients with HF is still controversial. A recent reduction in the annual rate of SCD has been recently described but it is not clear if this is also true in advanced age patients. Age is associated with SCD, although physicians frequently have the perception that elderly patients with HF die mainly of pump failure, underestimating the importance of SCD. Other clinical variables that have been associated to SCD are symptoms, New York Heart Association functional class, ischemic cause, and comorbidities (chronic obstructive pulmonary disease, renal dysfunction and diabetes). Some test results that should also be considered are left ventricular ejection fraction and diameters, natriuretic peptides, non-sustained ventricular tachycardias and autonomic abnormalities. The combination of all these markers is probably the best option to predict SCD. Different risk scores have been described and, although there are no specific ones for elderly populations, most include age as a risk predictor and some were developed in populations with mean age > 65 years. Finally, it is important to stress that these scores should be able to predict any type of SCD as, although most are due to tachyarrhythmias, bradyarrhythmias also play a role, particularly in the case of the elderly.
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Affiliation(s)
- Ana Ayesta
- Cardiology Department, Hospital Universitario del Sureste, Arganda del Rey, Madrid, Spain
| | | | | | - Manuel Martínez-Sellés
- Universidad Complutense, Madrid, Spain
- Cardiology Department, Hospital General Universitario Gregorio Marañón, CIVERCV, Universidad Europea, Madrid, Spain
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Ramirez J, Orini M, Tucker JD, Pueyo E, Laguna P. Variability of Ventricular Repolarization Dispersion Quantified by Time-Warping the Morphology of the T-Waves. IEEE Trans Biomed Eng 2017; 64:1619-1630. [DOI: 10.1109/tbme.2016.2614899] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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The Application of Ambulatory Electrocardiographically-Based T-Wave Alternans in Patients with Arrhythmogenic Right Ventricular Dysplasia/Cardiomyopathy. Can J Cardiol 2016; 32:1355.e15-1355.e22. [DOI: 10.1016/j.cjca.2016.01.035] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2013] [Revised: 01/26/2016] [Accepted: 01/27/2016] [Indexed: 11/18/2022] Open
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Lewek J, Ptaszynski P, Klingenheben T, Cygankiewicz I. The clinical value of T-wave alternans derived from Holter monitoring. Europace 2016; 19:529-534. [DOI: 10.1093/europace/euw292] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2016] [Accepted: 08/19/2016] [Indexed: 11/12/2022] Open
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15
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Burattini L, Man S, Fioretti S, Di Nardo F, Swenne CA. Heart Rate-Dependent Hysteresis of T-Wave Alternans in Primary Prevention ICD Patients. Ann Noninvasive Electrocardiol 2015; 21:460-9. [PMID: 26671620 DOI: 10.1111/anec.12330] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
Abstract
BACKGROUND T-wave alternans (TWA) is usually performed at accelerated heart rates (HR) during exercise, while recovery TWA is typically not analyzed. Consequently, it is still unknown if TWA shows a HR-dependent hysteresis or not. Thus, the aim of the present study was to investigate TWA dependency on HR during both the exercise and recovery phases of an ergometer test, and to evaluate if recovery TWA may contribute to identify subjects at increased risk of arrhythmic events. METHODS Our HR adaptive match filter was used to identify TWA from electrocardiographic recordings acquired during a bicycle ergometer test in 266 patients with implanted cardio-defibrillator. During the 4-year follow-up, 76 patients developed tachycardia or ventricular fibrillation (ICD_Cases) and 190 did not (ICD_Controls). RESULTS TWA was statistically lower during exercise than recovery for HRs between 75 and 110 bpm (16-21 μV vs 20-27 μV; P < 0.05), and reverse for HRs between 120 and 130 bpm (41-51 μV vs 28 μV; P < 0.05). ICD_Cases and ICD_Controls showed significantly different TWA at 80 bpm (20 μV vs 15 μV; P < 0.05) and 140 bpm (15 μV vs 22 μV; P < 0.05) during exercise, and at 90 bpm (38 μV vs 21 μV; P < 0.05) and 95 bpm (33-24 μV vs 28 μV; P < 0.05) during recovery. CONCLUSIONS TWA shows a HR-dependent hysteresis and there is a different behavior of TWA in ICD_Cases and ICD_Controls groups. Consequently, beside exercise TWA also recovery TWA may contribute to identify subjects at increased risk of arrhythmic events.
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Affiliation(s)
- Laura Burattini
- Department of Information Engineering, Polytechnic University of Marche, Ancona, Italy
| | - Sumche Man
- Department of Cardiology, Leiden University Medical Center, Leiden, The Netherlands
| | - Sandro Fioretti
- Department of Information Engineering, Polytechnic University of Marche, Ancona, Italy
| | - Francesco Di Nardo
- Department of Information Engineering, Polytechnic University of Marche, Ancona, Italy
| | - Cees A Swenne
- Department of Cardiology, Leiden University Medical Center, Leiden, The Netherlands
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PADFIELD GARETHJ, STEINBERG CHRISTIAN, YEUNG-LAI-WAH JOHNA. Intracardiac T-Wave Alternans and Ventricular Arrhythmia in Long-QT Syndrome. J Cardiovasc Electrophysiol 2015; 26:1155-6. [DOI: 10.1111/jce.12668] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- GARETH J. PADFIELD
- Heart Centre, St. Paul's Hospital; University of British Columbia; Vancouver Canada
| | - CHRISTIAN STEINBERG
- Heart Centre, St. Paul's Hospital; University of British Columbia; Vancouver Canada
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17
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Noise processing in exercise ECG stress test for the analysis and the clinical characterization of QRS and T wave alternans. Biomed Signal Process Control 2015. [DOI: 10.1016/j.bspc.2015.02.003] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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18
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Janusek D, Kania M, Zaczek R, Kobylecka M, Chojnowski M, Królicki L, Opolski G, Maniewski R. Evaluation of T-wave alternans in high-resolution ECG maps recorded during the stress test in patients after myocardial infarction. Arch Med Sci 2015; 11:99-105. [PMID: 25861295 PMCID: PMC4379364 DOI: 10.5114/aoms.2013.39939] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/27/2013] [Revised: 10/05/2013] [Accepted: 10/09/2013] [Indexed: 11/22/2022] Open
Abstract
INTRODUCTION Recent studies point to analysis of T-wave alternans as a promising indicator of an increased risk of life-threatening ventricular arrhythmias. In this study the occurrence of T-wave alternans in the high-resolution ECGs recorded during the exercise stress test and scintigraphic tests (SPECT) in patients with ischemic heart disease was examined. MATERIAL AND METHODS The study group consisted of 33 patients after myocardial infarction. In the group of patients after myocardial infarction and with low left ventricular ejection fraction correlations of 70% between the test results of T-wave alternans and SPECT and 60% between the test results of T-wave alternans and stress test were found. RESULTS In the group of patients after myocardial infarction but with high left ventricular ejection fraction correlations were respectively 39% and 48%. The analysis of the electrocardiographic maps showed a strong dependence of this correlation on the T-wave alternans amplitude and location of the ECG measuring electrode on the chest. The results might suggest that in patients after myocardial infarction and at increased risk for sudden cardiac death T-wave alternans may also provide information about cardiac electrical instability associated with ischemia. CONCLUSIONS It can also be assumed that the position of the electrode where the highest level of the T-wave alternans was detected can indicate the location of the ischemic region of the heart.
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Affiliation(s)
- Dariusz Janusek
- Nalecz Institute of Biocybernetics and Biomedical Engineering, Polish Academy of Sciences, Warsaw, Poland
| | - Michał Kania
- Nalecz Institute of Biocybernetics and Biomedical Engineering, Polish Academy of Sciences, Warsaw, Poland
| | - Rajmund Zaczek
- Department of Cardiology, Medical University of Warsaw, Warsaw, Poland
| | | | - Marek Chojnowski
- Department of Nuclear Medicine, Medical University of Warsaw, Warsaw, Poland
| | - Leszek Królicki
- Department of Nuclear Medicine, Medical University of Warsaw, Warsaw, Poland
| | - Grzegorz Opolski
- Department of Cardiology, Medical University of Warsaw, Warsaw, Poland
| | - Roman Maniewski
- Nalecz Institute of Biocybernetics and Biomedical Engineering, Polish Academy of Sciences, Warsaw, Poland
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Klingenheben T. [Microvolt T-wave alternans. Ischemic vs. nonischemic dilated cardiomyopathy]. Herzschrittmacherther Elektrophysiol 2015; 26:22-26. [PMID: 25693483 DOI: 10.1007/s00399-015-0353-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2014] [Accepted: 01/26/2015] [Indexed: 06/04/2023]
Abstract
The use of implantable cardioverter defibrillators (ICD) for primary preventive therapy of sudden arrhythmogenic death has become a mainstay in selected patients with systolic congestive heart failure, particularly in the setting of ischemic and nonischemic cardiomyopathy (Moss et al., N Engl J Med 346:877–883, 2002; Bardy et al., N Engl J Med 352:225–237, 2005). However, more accurate identification of high-risk patients is desirable in order to avoid unnecessary ICD implants. Since currently available risk stratification methods have limited predictive accuracy, development of new techniques is important in order to noninvasively assess arrhythmogenic risk in patients prone to sudden death.Microvolt level T-wave alternans (mTWA) has recently been proposed to assess abnormalities in ventricular repolarization favoring the occurrence of reentrant arrhythmias (Adam et al., J Electrocardiol 17:209–218, 1984; Pastore et al., Circulation 99:1385–1394, 1999). In 1994, a preliminary clinical study by Rosenbaum et al. convincingly demonstrated that mTWA is closely related to arrhythmia induction in the electrophysiology laboratory as well as to the occurrence of spontaneous ventricular tachyarrhythmias during follow-up (Rosenbaum et al., N Engl J Med 330:235–241,1994). More recently, a number of clinical studies have examined its clinical applicability in ischemic and nonischemic cardiomyopathy.
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Affiliation(s)
- Thomas Klingenheben
- Praxis für Kardiologie & Ambulante Herzkatheterkooperation Bonn, Im Mühlenbach 2 B, 53127, Bonn, Deutschland,
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20
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Safavi-Naeini P, Rasekh A, Razavi M, Saeed M, Massumi A. Sudden Cardiac Death in Coronary Artery Disease. Coron Artery Dis 2015. [DOI: 10.1007/978-1-4471-2828-1_24] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Burattini L, Man S, Fioretti S, Di Nardo F, Swenne CA. Dependency of exercise-induced T-wave alternans predictive power for the occurrence of ventricular arrhythmias from heart rate. Ann Noninvasive Electrocardiol 2014; 20:345-54. [PMID: 25367434 DOI: 10.1111/anec.12224] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
BACKGROUND T-wave alternans (TWA) is a noninvasive index of risk for the occurrence of ventricular arrhythmias. It is known that TWA amplitude (TWAA) increases with heart rate (HR) but how the TWA predictive power varies with HR remains unknown. Thus, the aim of this study was to evaluate the dependency of exercise-induced TWA predictive power for the occurrence of ventricular arrhythmias from HR. METHODS TWA was identified using our HR adaptive match filter in exercise ECGs from 248 patients with implanted cardiac defibrillator (ICD), of which 72 developed ventricular tachycardia and/or fibrillation during the 4 year follow-up (ICD_Cases) and 176 did not (ICD_Controls). TWA predictive power was evaluated at HRs from 80 to 120 bpm by computing the area under the receiver operating characteristic curve (AUC) obtained using the maximum TWAA (maxTWAA) and the TWAA ratio (TWAAratio; i.e., the ratio between TWAA at a specific HR and at 80 bpm). RESULTS TWAA increased with HR. At 80 bpm maxTWAA was lower than at 120 bpm in both ICD_Cases (22 μV vs 41 μV; P < 10(-2) ) and ICD_ Controls (16 μV vs 36 μV; P < 10(-4) ). However, only at 80 bpm ICD_Cases showed significantly higher maxTWAA than ICD_Controls (AUC = 0.6486; P = 0.0080). TWAAratio was higher in ICD_Controls than ICD_Cases for all HR but 120 bpm, and its predictive power was maximum at 115 bpm (AUC = 0.6914; P < 0.05). CONCLUSIONS Exercise-induced TWA predictive power for the occurrence of ventricular arrhythmias, quantified using both maxTWAA and TWAAratio, was higher at low rather than at high HR.
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Affiliation(s)
- Laura Burattini
- Department of Information Engineering, Polytechnic University of Marche, Ancona, Italy.,B.M.E.D. Bio-Medical Engineering Development SRL, Department of Information Engineering, Polytechnic University of Marche, Ancona, Italy
| | - Sumche Man
- Department of Cardiology, Leiden University Medical Center, Leiden, The Netherlands
| | | | - Francesco Di Nardo
- Department of Information Engineering, Polytechnic University of Marche, Ancona, Italy
| | - Cees A Swenne
- B.M.E.D. Bio-Medical Engineering Development SRL, Department of Information Engineering, Polytechnic University of Marche, Ancona, Italy
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Pezawas T, Diedrich A, Winker R, Robertson D, Richter B, Wang L, Byrne DW, Schmidinger H. Multiple autonomic and repolarization investigation of sudden cardiac death in dilated cardiomyopathy and controls. Circ Arrhythm Electrophysiol 2014; 7:1101-8. [PMID: 25262115 DOI: 10.1161/circep.114.001745] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
BACKGROUND Prophylactic defibrillator implantation is recommended in dilated, nonischemic heart disease and left ventricular ejection fraction of ≤0.30 to 0.35. Noninvasive testing should improve accuracy in decision making of prophylactic defibrillator implantation. METHODS AND RESULTS We enrolled 60 patients (median age, 57 years) with dilated cardiomyopathy and left ventricular ejection fraction ≤0.50, and 30 control subjects (median age, 59 years) with left ventricular ejection fraction >0.50. The protocol included an initial assessment, a second assessment after 3 years, and a final follow-up: pharmacological baroreflex testing (baroreceptor reflex sensitivity), short-term spectral analysis of heart rate variability (low frequency/high frequency), and long-term time domain analysis (SD of all normal-to-normal R-R intervals), exercise microvolt T wave alternans, and signal-averaged ECG, and corrected QT-time. The median follow-up was 7 years. End points were cardiac death, resuscitated cardiac arrest, and arrhythmic death. Cardiac death was observed in 21 patients. Resuscitated cardiac arrest and arrhythmic death caused by ventricular tachyarrhythmias ≥240 per minute was observed in 7 and 10 patients, respectively. In the single time point analysis, microvolt T wave alternans, baroreceptor reflex sensitivity, and SD of all normal-to-normal R-R intervals at initial testing added significant information regarding cardiac death. Microvolt T wave alternans added information on resuscitated cardiac arrest or arrhythmic death at multiple time points (P<0.001). False-negative microvolt T wave alternans results were seen in 8% of patients. CONCLUSIONS Noninvasive testing and left ventricular ejection fraction could not reliably identify patients with dilated cardiomyopathy at risk of fatal ventricular tachyarrhythmias. Therefore, the strategy to confine prophylactic implantable cardioverter-defibrillator implantation to patients with dilated cardiomyopathy and severely reduced LV function should be reconsidered.
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Affiliation(s)
- Thomas Pezawas
- From the Division of Cardiology, Department of Internal Medicine II, Medical University of Vienna, Vienna, Austria (T.P., B.R., H.S.); Departments of Medicine (A.D.), and Departments of Medicine, Pharmacology, Neurology (D.R.), Division of Clinical Pharmacology, Vanderbilt Autonomic Dysfunction Center, Vanderbilt University School of Medicine, Nashville, TN; Health and Prevention Center, Sanatorium Hera, Vienna, Austria (R.W.); and Department of Biostatistics, Vanderbilt University School of Medicine, Nashville, TN (L.W., D.W.B.).
| | - André Diedrich
- From the Division of Cardiology, Department of Internal Medicine II, Medical University of Vienna, Vienna, Austria (T.P., B.R., H.S.); Departments of Medicine (A.D.), and Departments of Medicine, Pharmacology, Neurology (D.R.), Division of Clinical Pharmacology, Vanderbilt Autonomic Dysfunction Center, Vanderbilt University School of Medicine, Nashville, TN; Health and Prevention Center, Sanatorium Hera, Vienna, Austria (R.W.); and Department of Biostatistics, Vanderbilt University School of Medicine, Nashville, TN (L.W., D.W.B.)
| | - Robert Winker
- From the Division of Cardiology, Department of Internal Medicine II, Medical University of Vienna, Vienna, Austria (T.P., B.R., H.S.); Departments of Medicine (A.D.), and Departments of Medicine, Pharmacology, Neurology (D.R.), Division of Clinical Pharmacology, Vanderbilt Autonomic Dysfunction Center, Vanderbilt University School of Medicine, Nashville, TN; Health and Prevention Center, Sanatorium Hera, Vienna, Austria (R.W.); and Department of Biostatistics, Vanderbilt University School of Medicine, Nashville, TN (L.W., D.W.B.)
| | - David Robertson
- From the Division of Cardiology, Department of Internal Medicine II, Medical University of Vienna, Vienna, Austria (T.P., B.R., H.S.); Departments of Medicine (A.D.), and Departments of Medicine, Pharmacology, Neurology (D.R.), Division of Clinical Pharmacology, Vanderbilt Autonomic Dysfunction Center, Vanderbilt University School of Medicine, Nashville, TN; Health and Prevention Center, Sanatorium Hera, Vienna, Austria (R.W.); and Department of Biostatistics, Vanderbilt University School of Medicine, Nashville, TN (L.W., D.W.B.)
| | - Bernhard Richter
- From the Division of Cardiology, Department of Internal Medicine II, Medical University of Vienna, Vienna, Austria (T.P., B.R., H.S.); Departments of Medicine (A.D.), and Departments of Medicine, Pharmacology, Neurology (D.R.), Division of Clinical Pharmacology, Vanderbilt Autonomic Dysfunction Center, Vanderbilt University School of Medicine, Nashville, TN; Health and Prevention Center, Sanatorium Hera, Vienna, Austria (R.W.); and Department of Biostatistics, Vanderbilt University School of Medicine, Nashville, TN (L.W., D.W.B.)
| | - Li Wang
- From the Division of Cardiology, Department of Internal Medicine II, Medical University of Vienna, Vienna, Austria (T.P., B.R., H.S.); Departments of Medicine (A.D.), and Departments of Medicine, Pharmacology, Neurology (D.R.), Division of Clinical Pharmacology, Vanderbilt Autonomic Dysfunction Center, Vanderbilt University School of Medicine, Nashville, TN; Health and Prevention Center, Sanatorium Hera, Vienna, Austria (R.W.); and Department of Biostatistics, Vanderbilt University School of Medicine, Nashville, TN (L.W., D.W.B.)
| | - Daniel W Byrne
- From the Division of Cardiology, Department of Internal Medicine II, Medical University of Vienna, Vienna, Austria (T.P., B.R., H.S.); Departments of Medicine (A.D.), and Departments of Medicine, Pharmacology, Neurology (D.R.), Division of Clinical Pharmacology, Vanderbilt Autonomic Dysfunction Center, Vanderbilt University School of Medicine, Nashville, TN; Health and Prevention Center, Sanatorium Hera, Vienna, Austria (R.W.); and Department of Biostatistics, Vanderbilt University School of Medicine, Nashville, TN (L.W., D.W.B.)
| | - Herwig Schmidinger
- From the Division of Cardiology, Department of Internal Medicine II, Medical University of Vienna, Vienna, Austria (T.P., B.R., H.S.); Departments of Medicine (A.D.), and Departments of Medicine, Pharmacology, Neurology (D.R.), Division of Clinical Pharmacology, Vanderbilt Autonomic Dysfunction Center, Vanderbilt University School of Medicine, Nashville, TN; Health and Prevention Center, Sanatorium Hera, Vienna, Austria (R.W.); and Department of Biostatistics, Vanderbilt University School of Medicine, Nashville, TN (L.W., D.W.B.)
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Iacoviello M, Monitillo F. Non-invasive evaluation of arrhythmic risk in dilated cardiomyopathy: From imaging to electrocardiographic measures. World J Cardiol 2014; 6:562-576. [PMID: 25068017 PMCID: PMC4110605 DOI: 10.4330/wjc.v6.i7.562] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/29/2013] [Revised: 03/29/2014] [Accepted: 05/19/2014] [Indexed: 02/06/2023] Open
Abstract
Malignant ventricular arrhythmias are a major adverse event and worsen the prognosis of patients affected by ischemic and non-ischemic dilated cardiomyopathy. The main parameter currently used to stratify arrhythmic risk and guide decision making towards the implantation of a cardioverter defibrillator is the evaluation of the left ventricular ejection fraction. However, this strategy is characterized by several limitations and consequently additional parameters have been suggested in order to improve arrhythmic risk stratification. The aim of this review is to critically revise the prognostic significance of non-invasive diagnostic tools in order to better stratify the arrhythmic risk prognosis of dilated cardiomyopathy patients.
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Lu P, Gong Y, Chen Y, Cai W, Sheng J. Safety analysis of tooth extraction in elderly patients with cardiovascular diseases. Med Sci Monit 2014; 20:782-8. [PMID: 24819043 PMCID: PMC4031223 DOI: 10.12659/msm.890131] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Background This study aimed to evaluate the safety of tooth extraction in elderly patients with cardiovascular diseases. Material/Methods A total of 13 527 patients underwent tooth extraction at the Affiliated Ninth People’s Hospital of Shanghai Jiaotong University. Age, sex, and diseases were analyzed. Cardiac monitoring during tooth extraction was performed in 7077 elderly patients with hypertension and other chronic diseases, and the influence of various factors on safety of tooth extraction was evaluated. Additionally, 89 patients with primary hypertension were recruited, and electrocardiogram was monitored with a general monitor or a Holter monitor, and the detection rate of cardiovascular events was compared between the 2 groups. Results The elderly accounted from 75.3%, and patients aged 70–79 years had highest proportion. The most frequent comorbidities were hypertension, coronary heart disease, arrhythmia, cerebrovascular accident, and diabetes. In analysis of factors influencing the safety of tooth extraction in the elderly, a significant difference was noted in systolic blood pressure at different time points. In addition, change in heart rate was different between males and females. Detection rate of cardiovascular events by use of a Holter monitor was significantly higher than with a general monitor. Conclusions Hypertension was the most common comorbidity in elderly patients undergoing tooth extraction, followed by coronary heart disease and arrhythmia. Advanced age and increased comorbidity may increase the risk of complications. Risk score can be used to rapidly determine risk for complications during tooth extraction. The Holter monitor is superior to the general monitor in identifying cardiovascular events in high-risk elderly patients undergoing tooth extraction, and can be used in this population.
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Affiliation(s)
- Ping Lu
- Department of Geriatrics, Affiliated Ninth People's Hospital, Shanghai Jiaotong University School of Medicine, Shanghai, China (mainland)
| | - Yiwen Gong
- Department of Geriatrics, Affiliated Ninth People's Hospital, Shanghai Jiaotong University School of Medicine, Shanghai, China (mainland)
| | - Yi Chen
- Department of Geriatrics, Affiliated Ninth People's Hospital, Shanghai Jiaotong University School of Medicine, Shanghai, China (mainland)
| | - Wenwei Cai
- Department of Geriatrics, Affiliated Ninth People's Hospital, Shanghai Jiaotong University School of Medicine, Shanghai, China (mainland)
| | - Jing Sheng
- Department of Geriatrics, Affiliated Ninth People's Hospital, Shanghai Jiaotong University School of Medicine, Shanghai, China (mainland)
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Bini S, Burattini L. Quantitative characterization of repolarization alternans in terms of amplitude and location: What information from different methods? Biomed Signal Process Control 2013. [DOI: 10.1016/j.bspc.2013.06.012] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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Molon G, Cohen RJ, de Santo T, Costa A, Barbieri E. Clinical use of microvolt T-wave alternans in patients with depressed left ventricular function eligible for ICD implantation: mortality outcomes after long term follow-up. Int J Cardiol 2013; 168:3038-40. [PMID: 23643438 DOI: 10.1016/j.ijcard.2013.04.133] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/04/2013] [Accepted: 04/06/2013] [Indexed: 11/24/2022]
Affiliation(s)
- Giulio Molon
- Cardiology Department, Sacro Cuore Hospital, Negrar, Verona, Italy.
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A combined anatomic and electrophysiologic substrate based approach for sudden cardiac death risk stratification. Am Heart J 2013; 166:744-52. [PMID: 24093856 DOI: 10.1016/j.ahj.2013.06.023] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/31/2013] [Accepted: 06/30/2013] [Indexed: 12/20/2022]
Abstract
BACKGROUND Although left ventricular ejection fraction (LVEF) is the primary determinant for sudden cardiac death (SCD) risk stratification, in isolation, LVEF is a sub-optimal risk stratifier. We assessed whether a multi-marker strategy would provide more robust SCD risk stratification than LVEF alone. METHODS We collected patient-level data (n = 3355) from 6 studies assessing the prognostic utility of microvolt T-wave alternans (MTWA) testing. Two thirds of the group was used for derivation (n = 2242) and one-third for validation (n = 1113). The discriminative capacity of the multivariable model was assessed using the area under the receiver-operating characteristic curve (c-index). The primary endpoint was SCD at 24 months. RESULTS In the derivation cohort, 59 patients experienced SCD by 24 months. Stepwise selection suggested that a model based on 3 parameters (LVEF, coronary artery disease and MTWA status) provided optimal SCD risk prediction. In the derivation cohort, the c-index of the model was 0.817, which was significantly better than LVEF used as a single variable (0.637, P < .001). In the validation cohort, 36 patients experienced SCD by 24 months. The c-index of the model for predicting the primary endpoint was again significantly better than LVEF alone (0.774 vs 0.671, P = .020). CONCLUSIONS A multivariable model based on presence of coronary artery disease, LVEF and MTWA status provides significantly more robust SCD risk prediction than LVEF as a single risk marker. These findings suggest that multi-marker strategies based on different aspects of the electro-anatomic substrate may be capable of improving primary prevention implantable cardioverter-defibrillator treatment algorithms.
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Burattini L, Man S, Sweene CA. The power of exercise-induced T-wave alternans to predict ventricular arrhythmias in patients with implanted cardiac defibrillator. JOURNAL OF HEALTHCARE ENGINEERING 2013; 4:167-84. [PMID: 23778010 DOI: 10.1260/2040-2295.4.2.167] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
The power of exercise-induced T-wave alternans (TWA) to predict the occurrence of ventricular arrhythmias was evaluated in 67 patients with an implanted cardiac defibrillator (ICD). During the 4-year follow-up, electrocardiographic (ECG) tracings were recorded in a bicycle ergometer test with increasing workload ranging from zero (NoWL) to the patient's maximal capacity (MaxWL). After the follow-up, patients were classified as either ICD_Cases (n = 29), if developed ventricular tachycardia/fibrillation, or ICD_Controls (n = 38). TWA was quantified using our heart-rate adaptive match filter. Compared to NoWL, MaxWL was characterized by faster heart rates and higher TWA in both ICD_Cases (12-18 μ V vs. 20-39 μ V; P < 0.05) and ICD_Controls (9-15 μ V vs. 20-32 μ V; P < 0.05). Still, TWA was able to discriminate the two ICD groups during NoWL (sensitivity = 59-83%, specificity = 53-84%) but not MaxWL (sensitivity = 55-69%, specificity = 39-74%). Thus, this retrospective observational case-control study suggests that TWA's predictive power for the occurrence of ventricular arrhythmias could increase at low heart rates.
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Affiliation(s)
- Laura Burattini
- Department of Information Engineering, Polytechnic University of Marche, Ancona, Italy.
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29
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A unified procedure for detecting, quantifying, and validating electrocardiogram T-wave alternans. Med Biol Eng Comput 2013; 51:1031-42. [DOI: 10.1007/s11517-013-1084-z] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2013] [Accepted: 05/11/2013] [Indexed: 10/26/2022]
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Burattini L, Man S, Burattini R, Swenne CA. Comparison of standard versus orthogonal ECG leads for T-wave alternans identification. Ann Noninvasive Electrocardiol 2012; 17:130-40. [PMID: 22537331 DOI: 10.1111/j.1542-474x.2012.00490.x] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
Abstract
T-wave alternans (TWA), an electrophysiologic phenomenon associated with ventricular arrhythmias, is usually detected from selected ECG leads. TWA amplitude measured in the 12-standard and the 3-orthogonal (vectorcardiographic) leads were compared here to identify which lead system yields a more adequate detection of TWA as a noninvasive marker for cardiac vulnerability to ventricular arrhythmias. Our adaptive match filter (AMF) was applied to exercise ECG tracings from 58 patients with an implanted cardiac defibrillator, 29 of which had ventricular tachycardia or fibrillation during follow-up (cases), while the remaining 29 were used as controls. Two kinds of TWA indexes were considered, the single-lead indexes, defined as the mean TWA amplitude over each lead (MTWAA), and lead-system indexes, defined as the mean and the maximum MTWAA values over the standard leads and over the orthogonal leads. Significantly (P < 0.05) higher TWA in the cases versus controls was identified only occasionally by the single-lead indexes (odds ratio: 1.0-9.9, sensitivity: 24-76%, specificity: 76-86%), and consistently by the lead-system indexes (odds ratio: 4.5-8.3, sensitivity: 57-72%, specificity: 76%). The latter indexes also showed a significant correlation (0.65-0.83) between standard and orthogonal leads. Hence, when using the AMF, TWA should be detected in all leads of a system to compute the lead-system indexes, which provide a more reliable TWA identification than single-lead indexes, and a better discrimination of patients at increased risk of cardiac instability. The standard and the orthogonal leads can be considered equivalent for TWA identification, so that TWA analysis can be limited to one-lead system.
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Affiliation(s)
- Laura Burattini
- Department of Information Engineering, Polytechnic University of Marche, Ancona, Italy.
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Wijers SC, Vos MA, Meine M. Microvolt T-wave alternans in an unselected heart failure population: pros and cons. Eur J Heart Fail 2012; 14:344-7. [PMID: 22431405 DOI: 10.1093/eurjhf/hfs032] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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32
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Burattini L, Zareba W, Burattini R. Is T-wave alternans T-wave amplitude dependent? Biomed Signal Process Control 2012. [DOI: 10.1016/j.bspc.2011.06.009] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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Iravanian S, Kanu UB, Christini DJ. A class of Monte-Carlo-based statistical algorithms for efficient detection of repolarization alternans. IEEE Trans Biomed Eng 2012; 59:1882-91. [PMID: 22481808 DOI: 10.1109/tbme.2012.2192733] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Cardiac repolarization alternans is an electrophysiologic condition identified by a beat-to-beat fluctuation in action potential waveform. It has been mechanistically linked to instances of T-wave alternans, a clinically defined ECG alternation in T-wave morphology, and associated with the onset of cardiac reentry and sudden cardiac death. Many alternans detection algorithms have been proposed in the past, but the majority have been designed specifically for use with T-wave alternans. Action potential duration (APD) signals obtained from experiments (especially those derived from optical mapping) possess unique characteristics, which requires the development and use of a more appropriate alternans detection method. In this paper, we present a new class of algorithms, based on the Monte Carlo method, for the detection and quantitative measurement of alternans. Specifically, we derive a set of algorithms (one an analytical and more efficient version of the other) and compare its performance with the standard spectral method and the generalized likelihood ratio test algorithm using synthetic APD sequences and optical mapping data obtained from an alternans control experiment. We demonstrate the benefits of the new algorithm in the presence of Gaussian and Laplacian noise and frame-shift errors. The proposed algorithms are well suited for experimental applications, and furthermore, have low complexity and are implementable using fixed-point arithmetic, enabling potential use with implantable cardiac devices.
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Affiliation(s)
- Shahriar Iravanian
- Division of Cardiology, Emory University School of Medicine, Atlanta, GA 30322, USA.
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Clinical utility of microvolt T-wave alternans testing in identifying patients at high or low risk of sudden cardiac death. Heart Rhythm 2012; 9:1256-64.e2. [PMID: 22406384 DOI: 10.1016/j.hrthm.2012.03.014] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/03/2012] [Indexed: 02/07/2023]
Abstract
BACKGROUND Previous studies have demonstrated that microvolt T-wave alternans (MTWA) testing is a robust predictor of ventricular tachyarrhythmias and sudden cardiac death (SCD) in at-risk patients. However, recent studies have suggested that MTWA testing is not as good a predictor of "appropriate" implantable cardioverter-defibrillator (ICD) therapy as it is a predictor of SCD in patients without ICDs. OBJECTIVE To evaluate the utility of MTWA testing for SCD risk stratification in patients without ICDs. METHODS Patient-level data were obtained from 5 prospective studies of MTWA testing in patients with no history of ventricular arrhythmia or SCD. In these studies, ICDs were implanted in only a minority of patients and patients with ICDs were excluded from the analysis. We conducted a pooled analysis and examined the 2-year risk for SCD based on the MTWA test result. RESULTS The pooled cohort included 2883 patients. MTWA testing was positive in 856 (30%), negative in 1627 (56%), and indeterminate in 400 (14%) patients. Among patients with a left ventricular ejection fraction (LVEF) of ≤35%, annual SCD event rates were 4.0%, 0.9%, and 4.6% among groups with MTWA positive, negative, and indeterminate test results. The SCD rate was significantly lower among patients with a negative MTWA test result than in patients with either positive or indeterminate MTWA test results (P <.001 for both comparisons). In patients with an LVEF of >35%, annual SCD event rates were 3.0%, 0.3%, and 0.3% among the groups with MTWA positive, negative, and indeterminate test results. The SCD rate associated with a positive MTWA test result was significantly higher than that associated with either negative (P <.001) or indeterminate MTWA test results (P = .003). CONCLUSIONS In patients without ICDs, MTWA testing is a powerful predictor of SCD. Among patients with an LVEF of ≤35%, a negative MTWA test result is associated with a low risk for SCD. Conversely, among patients with an LVEF of >35%, a positive MTWA test result identifies patients at significantly heightened SCD risk. These findings may have important implications for refining primary prevention ICD treatment algorithms.
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Ability of microvolt T-wave alternans to modify risk assessment of ventricular tachyarrhythmic events: a meta-analysis. Am Heart J 2012; 163:354-64. [PMID: 22424005 DOI: 10.1016/j.ahj.2011.11.021] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/18/2011] [Accepted: 11/30/2011] [Indexed: 02/08/2023]
Abstract
BACKGROUND Prior studies have indicated that the magnitude of risk association of microvolt T-wave alternans (MTWA) testing appears to vary with the population studied. We performed a meta-analysis to determine the ability of MTWA to modify risk assessment of ventricular tachyarrhythmic events (VTEs) and sudden cardiac death (SCD) across a series of patient risk profiles using likelihood ratio (LR) testing, a measure of test performance independent of disease prevalence. METHODS We identified original research articles published from January 1990 to January 2011 that investigate spectrally derived MTWA. Ventricular tachyarrhythmic event was defined as the total and arrhythmic mortality and nonfatal sustained or implantable cardioverter-defibrillator-treated ventricular tachyarrhythmias. Summary estimates were created for positive and nonnegative MTWA results using a random-effects model and were expressed as positive (LR+) and negative (LR-) LRs. RESULTS Of 1,534 articles, 20 prospective cohort studies met our inclusion criteria, consisting of 5,945 subjects predominantly with prior myocardial infarction or left ventricular dysfunction. Although there was a modest association between positive MTWA and VTE (relative risk 2.45, 1.58-3.79) and nonnegative MTWA and VTE (3.68, 2.23-6.07), test performance was poor (positive MTWA: LR+ 1.78, LR- 0.43; nonnegative MTWA: LR+ 1.38, LR- 0.56). Subgroup analyses of subjects classified as prior VTE, post-myocardial infarction, SCD-HeFT type, and MADIT-II type had a similar poor test performance. A negative MTWA result would decrease the annualized risk of VTE from 8.85% to 6.37% in MADIT-II-type patients and from 5.91% to 2.60% in SCD-HeFT-type patients. CONCLUSIONS Despite a modest association, results of spectrally derived MTWA testing do not sufficiently modify the risk of VTE to change clinical decisions.
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Bortolan G, Christov I. T-wave alternans detection by a combined method of principal component analysis and T-wave amplitude. Physiol Meas 2012; 33:333-43. [DOI: 10.1088/0967-3334/33/3/333] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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Calò L, De Santo T, Nuccio F, Sciarra L, De Luca L, Stefano LMDS, Piroli E, Zuccaro L, Rebecchi M, de Ruvo E, Lioy E. Predictive value of microvolt T-wave alternans for cardiac death or ventricular tachyarrhythmic events in ischemic and nonischemic cardiomyopathy patients: a meta-analysis. Ann Noninvasive Electrocardiol 2012; 16:388-402. [PMID: 22008495 DOI: 10.1111/j.1542-474x.2011.00467.x] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
BACKGROUND Microvolt T-wave alternans (MTWA) has been proposed as a predictor of the risk of ventricular tachyarrhythmias (VT) and sudden cardiac death (SCD). Aim of this study was to perform a systematic review of the literature and a meta-analysis of MTWA in primary prevention patients with ischemic and nonischemic cardiomyopathy. METHODS The positive predictive value (PPV), negative predictive value (NPV), and relative risk (RR) of MTWA in predicting death, cardiac death, and SCD during follow-up were reported. RESULTS Fifteen studies involving 5681 patients (mean age 62 years, mean ejection fraction 32%) were included. The summary PPV during the average 26-month follow-up was 14% (95% CI: 13-15); NPV was 95% (95% CI: 94-96), and the univariate RR was 2.35 (95% CI: 1.68-3.28). The predictive value of MTWA was similar in patients with ischemic and nonischemic cardiomyopathy. The average RR for SCD or VT events of an abnormal MTWA was 2.40, similar to that for cardiac death. When we grouped the studies together depending upon whether beta-blockers were withheld prior to MTWA screening, the beta-blockers group showed an RR of 5.88. By contrast, the group in which beta-blocker therapy was withheld had an RR of 1.63. CONCLUSION A positive MTWA determined an approximately 2.5-fold higher risk of cardiac death and life-threatening arrhythmia and showed a very high NPV both in ischemic and nonischemic patients. An abnormal MTWA test was associated with a 5-fold increased risk for cardiac mortality in the low-indeterminate group and about a 6-fold increased risk in beta-blockers group.
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Affiliation(s)
- Leonardo Calò
- Division of Cardiology, Policlinico Casilino, ASL Roma B, Via Buonarroti 16, Marino, Rome, Italy.
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Jackson CE, Myles RC, Tsorlalis IK, Dalzell JR, Spooner RJ, Rodgers JR, Bezlyak V, Greenlaw N, Ford I, Cobbe SM, Petrie MC, McMurray JJV. Profile of microvolt T-wave alternans testing in 1003 patients hospitalized with heart failure. Eur J Heart Fail 2012; 14:377-86. [PMID: 22334727 DOI: 10.1093/eurjhf/hfs010] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
AIMS Observational studies in selected populations have suggested that microvolt T-wave alternans (MTWA) testing may identify patients with heart failure (HF) at risk of sudden cardiac death. The aims of this study were to investigate the utility of MTWA testing in an unselected population of patients with HF and to evaluate the clinical characteristics associated with the MTWA results. METHODS AND RESULTS A total of 1003 patients hospitalized with decompensated HF were enrolled. MTWA testing was planned 1 month post-discharge; 648 patients returned for MTWA testing. Mean age was 70.8 ± 10.6 years and 58% were male. Of these patients who returned, 318 (49%) were ineligible for MTWA testing due to atrial fibrillation (AF), pacemaker dependency, or physical inability to undertake the test. Of the MTWA tests, 100 (30%) were positive, 78 (24%) were negative, and 152 (46%) were indeterminate; 112/152 indeterminate tests (74%) occurred because of failure to achieve target heart rate (HR) due to chronotropic incompetence or physical limitations. There were differences in patient characteristics according to MTWA result. Independent predictors of a negative result included younger age and higher left ventricular ejection fraction (LVEF). Independent predictors of a positive result included higher HR during MTWA testing and lower LVEF. Independent predictors of an indeterminate result included older age and history of previous/paroxysmal AF. CONCLUSIONS Only half of patients with HF are eligible for MTWA testing and the most common result is an indeterminate test. Patients with positive and indeterminate tests have different clinical characteristics. MTWA treadmill testing is not widely applicable in typical HF patients and is unlikely to refine risk stratification for sudden death on a population level.
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Affiliation(s)
- Colette E Jackson
- British Heart Foundation Cardiovascular Research Centre, University of Glasgow, 126 University Place, Glasgow, UK
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Lou Q, Janardhan A, Efimov IR. Remodeling of calcium handling in human heart failure. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2012; 740:1145-74. [PMID: 22453987 PMCID: PMC3740791 DOI: 10.1007/978-94-007-2888-2_52] [Citation(s) in RCA: 82] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Heart failure (HF) is an increasing public health problem accelerated by a rapidly aging global population. Despite considerable progress in managing the disease, the development of new therapies for effective treatment of HF remains a challenge. To identify targets for early diagnosis and therapeutic intervention, it is essential to understand the molecular and cellular basis of calcium handling and the signaling pathways governing the functional remodeling associated with HF in humans. Calcium (Ca(2+)) cycling is an essential mediator of cardiac contractile function, and remodeling of calcium handling is thought to be one of the major factors contributing to the mechanical and electrical dysfunction observed in HF. Active research in this field aims to bridge the gap between basic research and effective clinical treatments of HF. This chapter reviews the most relevant studies of calcium remodeling in failing human hearts and discusses their connections to current and emerging clinical therapies for HF patients.
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Affiliation(s)
- Qing Lou
- Department of Biomedical Engineering, Washington University in St. Louis, 390E Whitaker Hall, One Brookings Drive, St. Louis, MO 63130, USA
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40
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Nearing BD, Wellenius GA, Mittleman MA, Josephson ME, Burger AJ, Verrier RL. Crescendo in depolarization and repolarization heterogeneity heralds development of ventricular tachycardia in hospitalized patients with decompensated heart failure. Circ Arrhythm Electrophysiol 2011; 5:84-90. [PMID: 22157521 DOI: 10.1161/circep.111.965434] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
BACKGROUND A critical need exists for reliable warning markers of in-hospital life-threatening arrhythmias. We used a new quantitative method to track interlead heterogeneity of depolarization and repolarization to detect premonitory changes before ventricular tachycardia (VT) in hospitalized patients with acute decompensated heart failure. METHODS AND RESULTS Ambulatory ECGs (leads V(1), V(5), and aVF) recorded before initiation of drug therapy from patients enrolled in the PRECEDENT (Prospective Randomized Evaluation of Cardiac Ectopy with Dobutamine or Nesiritide Therapy) trial were analyzed. R-wave heterogeneity (RWH) and T-wave heterogeneity (TWH) were assessed by second central moment analysis and T-wave alternans (TWA) by modified moving average analysis. Of 44 patients studied, 22 had experienced episodes of VT (≥4 beats at heart rates >100 beats/min) following ≥120 minutes of stable sinus rhythm, and 22 were age- and sex-matched patients without VT. TWA increased from 18.6±2.1 μV (baseline, mean±SEM) to 27.9±4.6 μV in lead V(5) at 15 to 30 minutes before VT (P<0.05) and remained elevated until the arrhythmia occurred. TWA results in leads V(1) and aVF were similar. RWH and TWH were elevated from 164.1±33.1 and 134.5±20.6 μV (baseline) to 299.8±54.5 and 239.2±37.0 μV at 30 to 45 minutes before VT (P<0.05), respectively, preceding the crescendo in TWA by 15 minutes. Matched patients without VT did not display elevated RWH (185.5±29.4 μV) or TWH (157.1±27.2 μV) during the 24-hour period. CONCLUSIONS This investigation is the first clinical demonstration of the potential utility of tracking depolarization and repolarization heterogeneity to detect crescendos in electrical instability that could forewarn of impending nonsustained VT. Clinical Trial Registration- URL: http://www.clinicaltrials.gov. Unique identifier: NCT00270400.
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Affiliation(s)
- Bruce D Nearing
- Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA 02215-3908, USA
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41
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Verrier RL, Klingenheben T, Malik M, El-Sherif N, Exner DV, Hohnloser SH, Ikeda T, Martínez JP, Narayan SM, Nieminen T, Rosenbaum DS. Microvolt T-wave alternans physiological basis, methods of measurement, and clinical utility--consensus guideline by International Society for Holter and Noninvasive Electrocardiology. J Am Coll Cardiol 2011; 58:1309-24. [PMID: 21920259 DOI: 10.1016/j.jacc.2011.06.029] [Citation(s) in RCA: 286] [Impact Index Per Article: 20.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/20/2011] [Revised: 06/10/2011] [Accepted: 06/13/2011] [Indexed: 10/17/2022]
Abstract
This consensus guideline was prepared on behalf of the International Society for Holter and Noninvasive Electrocardiology and is cosponsored by the Japanese Circulation Society, the Computers in Cardiology Working Group on e-Cardiology of the European Society of Cardiology, and the European Cardiac Arrhythmia Society. It discusses the electrocardiographic phenomenon of T-wave alternans (TWA) (i.e., a beat-to-beat alternation in the morphology and amplitude of the ST-segment or T-wave). This statement focuses on its physiological basis and measurement technologies and its clinical utility in stratifying risk for life-threatening ventricular arrhythmias. Signal processing techniques including the frequency-domain Spectral Method and the time-domain Modified Moving Average method have demonstrated the utility of TWA in arrhythmia risk stratification in prospective studies in >12,000 patients. The majority of exercise-based studies using both methods have reported high relative risks for cardiovascular mortality and for sudden cardiac death in patients with preserved as well as depressed left ventricular ejection fraction. Studies with ambulatory electrocardiogram-based TWA analysis with Modified Moving Average method have yielded significant predictive capacity. However, negative studies with the Spectral Method have also appeared, including 2 interventional studies in patients with implantable defibrillators. Meta-analyses have been performed to gain insights into this issue. Frontiers of TWA research include use in arrhythmia risk stratification of individuals with preserved ejection fraction, improvements in predictivity with quantitative analysis, and utility in guiding medical as well as device-based therapy. Overall, although TWA appears to be a useful marker of risk for arrhythmic and cardiovascular death, there is as yet no definitive evidence that it can guide therapy.
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Affiliation(s)
- Richard L Verrier
- Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, Massachusetts, USA
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42
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Shizuta S, Ando K, Nobuyoshi M, Ikeda T, Yoshino H, Hiramatsu S, Kazatani Y, Yamashiro K, Okajima K, Kajiya T, Kobayashi Y, Kato T, Fujii S, Mitsudo K, Inoue K, Ito H, Haruna Y, Doi T, Nishio Y, Ozasa N, Nishiyama K, Kita T, Morimoto T, Kimura T. Prognostic utility of T-wave alternans in a real-world population of patients with left ventricular dysfunction: the PREVENT-SCD study. Clin Res Cardiol 2011; 101:89-99. [PMID: 21960418 PMCID: PMC3268016 DOI: 10.1007/s00392-011-0368-2] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/09/2011] [Accepted: 09/15/2011] [Indexed: 10/25/2022]
Abstract
BACKGROUND The predictive value of T-wave alternans (TWA) for lethal ventricular tachyarrhythmia in patients with left ventricular (LV) dysfunction is controversial. Also, long-term arrhythmia risk of patients ineligible for the TWA test is unknown. METHODS This was a multicenter, prospective observational study of patients with LV ejection fraction ≤40% due to ischemic or non-ischemic cardiomyopathies, designed to evaluate the prognostic value of TWA for lethal ventricular tachyarrhythmia. The primary end point was a composite of sudden cardiac death, sustained rapid ventricular tachycardia (VT) or ventricular fibrillation (VF), and appropriate defibrillator therapy for rapid VT or VF. RESULTS Among 453 patients enrolled in the study, 280 (62%) were eligible for the TWA test. TWA was negative in 82 patients (29%), who accounted for 18% of the total population. The median of follow-up was 36 months. The 3-year event-free rate for the primary end point was significantly higher in TWA-negative patients (97.0%) than in TWA non-negative patients (89.5%, P = 0.037) and those ineligible for the TWA test (84.4%, P = 0.003). Multivariable analysis identified both non-negative TWA [hazard ratio (HR) 4.43; 95% confidence interval (CI) 1.02-19.2; P = 0.047) and ineligibility for the TWA test (HR 6.89; 95% CI 1.59-29.9; P = 0.010) to be independent predictors of the primary end point. CONCLUSIONS TWA showed high negative predictive ability for lethal ventricular tachyarrhythmia in patients with LV dysfunction, although the TWA-negative patients accounted for only 18% of the entire population. Those ineligible for the TWA test had the highest risk for lethal ventricular tachyarrhythmia.
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Affiliation(s)
- Satoshi Shizuta
- Department of Cardiovascular Medicine, Kyoto University Graduate School of Medicine, 54 Kawahara-cho, Shougoin, Sakyo-ku, Kyoto, 606-8507, Japan
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Repolarization alternans heterogeneity in healthy subjects and acute myocardial infarction patients. Med Eng Phys 2011; 34:305-12. [PMID: 21835679 DOI: 10.1016/j.medengphy.2011.07.019] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2011] [Revised: 07/15/2011] [Accepted: 07/19/2011] [Indexed: 11/22/2022]
Abstract
An association between heterogeneity of repolarization alternans (RA) and cardiac electrical instability has been reported. Characterization of RA in health and identification of physiological RA heterogeneity may help discrimination of abnormal RA cases more likely associated to arrhythmic events. Thus, aim of the present study was the identification of a physiological RA region in terms of mean temporal location (MRAD) with respect to the T apex, and mean amplitude (MRAA), by application of our heart-rate adaptive match filter method to clinical ECG recordings from 51 control healthy (CH) subjects and 43 acute myocardial infarction (AMI) patients. Results indicate that RA occurring within the first half of the T wave is dominant in both CH and AMI populations (74.5% and 53.5% of cases, respectively; P<0.05). Definition of physiological RA region in the MRAD vs. MRAA plane (-83 ms ≤ MRAD ≤ 23 ms, 0≤ MRAA ≤ 30 μV) provided 0% and 32.6% abnormal RA cases among the CH subjects and AMI patients, respectively. We conclude that myocardial infarction may associate with an RA occurring early (MRAD<-83 ms) or late (MRAD >23 ms) along the JT segment, in addition or in alternative to an abnormally high RA amplitude (MRAA >30 μV).
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Lopera G, Curtis AB. Risk stratification for sudden cardiac death: current approaches and predictive value. Curr Cardiol Rev 2011; 5:56-64. [PMID: 20066150 PMCID: PMC2803290 DOI: 10.2174/157340309787048130] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/27/2008] [Revised: 07/05/2008] [Accepted: 07/05/2008] [Indexed: 11/22/2022] Open
Abstract
Sudden cardiac death (SCD) is a serious public health problem; the annual incidence of out-of-hospital cardiac arrest in North America is approximately 166,200. Identifying patients at risk is a difficult proposition. At the present time, left ventricular ejection fraction (LVEF) remains the single most important marker for risk stratification. According to current guidelines, most patients with LVEF <35% could benefit from prophylactic ICD implantation, particularly in the setting of symptomatic heart failure. Current risk stratification strategies fail to identify patients at risk of SCD in larger population groups encompassing a greater number of potential SCD victims. However, the best approach to identifying patients and the value of various risk stratification tools is not entirely clear. The goal of this review is to discuss the problem of SCD and the value of the different risk stratification markers and their potential clinical use either alone or in combination with other risk stratification markers.
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Affiliation(s)
- Gustavo Lopera
- Division of Cardiology, University of Miami/Miller School of Medicine, Miami, FL, USA
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Bonapace S, Targher G, Molon G, Rossi A, Costa A, Zenari L, Bertolini L, Cian D, Lanzoni L, Barbieri E. Relationship Between Early Diastolic Dysfunction and Abnormal Microvolt T-Wave Alternans in Patients With Type 2 Diabetes. Circ Cardiovasc Imaging 2011; 4:408-14. [DOI: 10.1161/circimaging.110.962951] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Background—
Abnormal microvolt T-wave alternans (MTWA), a marker of ventricular arrhythmic risk, is a highly prevalent condition in patients with type 2 diabetes mellitus (T2DM) and is correlated with glycemic control. However, there is uncertainty as to whether central or peripheral hemodynamic factors are associated with abnormal MTWA in T2DM individuals.
Methods and Results—
We studied 50 consecutive, well-controlled T2DM outpatients without a history of ischemic heart disease and with normal systolic function. All patients underwent a complete echocardiographic Doppler evaluation with spectral tissue Doppler analysis. MTWA analysis was performed noninvasively during submaximal exercise. Effective arterial elastance, arterial compliance, and heart rate variability were also measured. Compared with patients with MTWA negativity (n=38), those with MTWA abnormality (n=12, 24%) had significantly lower e′ (7.6±1.3 versus 9.1±1.7 cm/s;
P
<0.01), a′ (10.2±1.6 versus 12.7±1.9 cm/s;
P
<0.001) and s′ velocities (8.7±1.1 versus 10.2±1.5 cm/s;
P
=0.001) and higher indexed left ventricular mass (121.3±16.4 versus 107.5±16.5 g/m
2
;
P
=0.016), indexed left atrial volume (33.5±11.9 versus 23.6±5.6 mL/m
2
;
P
<0.001), and E/e′ ratio (8.8±1.4 versus 6.5±1.3;
P
<0.001). Multivariable logistic regression analysis revealed that higher E/e′ ratio was the only independent correlate of abnormal MTWA (adjusted odds ratio, 3.52; 95% confidence interval, 1.19 to 10.6;
P
=0.02) after controlling for glycemic control and other potential confounders.
Conclusions—
In this pilot study, we found that early diastolic dysfunction, as measured by tissue Doppler imaging, is independently associated with MTWA abnormality in T2DM individuals with normal systolic function. Further larger studies are needed to examine the reproducibility of these results.
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Affiliation(s)
- Stefano Bonapace
- From the Division of Cardiology, Sacro Cuore Hospital, Negrar (VR), Italy (S.B., G.M., A.C., D.C., L.L., E.B.); the Section of Endocrinology and Metabolism, Department of Medicine, University of Verona, Italy (G.T.); the Section of Cardiology, Department of Medicine, University of Verona, Italy (A.R.); and the Diabetes Unit, Sacro Cuore Hospital, Negrar (VR), Italy (L.Z., L.B.)
| | - Giovanni Targher
- From the Division of Cardiology, Sacro Cuore Hospital, Negrar (VR), Italy (S.B., G.M., A.C., D.C., L.L., E.B.); the Section of Endocrinology and Metabolism, Department of Medicine, University of Verona, Italy (G.T.); the Section of Cardiology, Department of Medicine, University of Verona, Italy (A.R.); and the Diabetes Unit, Sacro Cuore Hospital, Negrar (VR), Italy (L.Z., L.B.)
| | - Giulio Molon
- From the Division of Cardiology, Sacro Cuore Hospital, Negrar (VR), Italy (S.B., G.M., A.C., D.C., L.L., E.B.); the Section of Endocrinology and Metabolism, Department of Medicine, University of Verona, Italy (G.T.); the Section of Cardiology, Department of Medicine, University of Verona, Italy (A.R.); and the Diabetes Unit, Sacro Cuore Hospital, Negrar (VR), Italy (L.Z., L.B.)
| | - Andrea Rossi
- From the Division of Cardiology, Sacro Cuore Hospital, Negrar (VR), Italy (S.B., G.M., A.C., D.C., L.L., E.B.); the Section of Endocrinology and Metabolism, Department of Medicine, University of Verona, Italy (G.T.); the Section of Cardiology, Department of Medicine, University of Verona, Italy (A.R.); and the Diabetes Unit, Sacro Cuore Hospital, Negrar (VR), Italy (L.Z., L.B.)
| | - Alessandro Costa
- From the Division of Cardiology, Sacro Cuore Hospital, Negrar (VR), Italy (S.B., G.M., A.C., D.C., L.L., E.B.); the Section of Endocrinology and Metabolism, Department of Medicine, University of Verona, Italy (G.T.); the Section of Cardiology, Department of Medicine, University of Verona, Italy (A.R.); and the Diabetes Unit, Sacro Cuore Hospital, Negrar (VR), Italy (L.Z., L.B.)
| | - Luciano Zenari
- From the Division of Cardiology, Sacro Cuore Hospital, Negrar (VR), Italy (S.B., G.M., A.C., D.C., L.L., E.B.); the Section of Endocrinology and Metabolism, Department of Medicine, University of Verona, Italy (G.T.); the Section of Cardiology, Department of Medicine, University of Verona, Italy (A.R.); and the Diabetes Unit, Sacro Cuore Hospital, Negrar (VR), Italy (L.Z., L.B.)
| | - Lorenzo Bertolini
- From the Division of Cardiology, Sacro Cuore Hospital, Negrar (VR), Italy (S.B., G.M., A.C., D.C., L.L., E.B.); the Section of Endocrinology and Metabolism, Department of Medicine, University of Verona, Italy (G.T.); the Section of Cardiology, Department of Medicine, University of Verona, Italy (A.R.); and the Diabetes Unit, Sacro Cuore Hospital, Negrar (VR), Italy (L.Z., L.B.)
| | - Debora Cian
- From the Division of Cardiology, Sacro Cuore Hospital, Negrar (VR), Italy (S.B., G.M., A.C., D.C., L.L., E.B.); the Section of Endocrinology and Metabolism, Department of Medicine, University of Verona, Italy (G.T.); the Section of Cardiology, Department of Medicine, University of Verona, Italy (A.R.); and the Diabetes Unit, Sacro Cuore Hospital, Negrar (VR), Italy (L.Z., L.B.)
| | - Laura Lanzoni
- From the Division of Cardiology, Sacro Cuore Hospital, Negrar (VR), Italy (S.B., G.M., A.C., D.C., L.L., E.B.); the Section of Endocrinology and Metabolism, Department of Medicine, University of Verona, Italy (G.T.); the Section of Cardiology, Department of Medicine, University of Verona, Italy (A.R.); and the Diabetes Unit, Sacro Cuore Hospital, Negrar (VR), Italy (L.Z., L.B.)
| | - Enrico Barbieri
- From the Division of Cardiology, Sacro Cuore Hospital, Negrar (VR), Italy (S.B., G.M., A.C., D.C., L.L., E.B.); the Section of Endocrinology and Metabolism, Department of Medicine, University of Verona, Italy (G.T.); the Section of Cardiology, Department of Medicine, University of Verona, Italy (A.R.); and the Diabetes Unit, Sacro Cuore Hospital, Negrar (VR), Italy (L.Z., L.B.)
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Dorenkamp M, Breitwieser C, Morguet AJ, Seegers J, Behrens S, Zabel M. T-wave alternans testing in pacemaker patients: comparison of pacing modes and long-term prognostic relevance. Pacing Clin Electrophysiol 2011; 34:1054-62. [PMID: 21501180 DOI: 10.1111/j.1540-8159.2011.03101.x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
BACKGROUND T-wave alternans (TWA) is a useful method for identifying patients who are at risk for sudden cardiac death. We aimed to determine the effects of different pacing modes on test results and long-term prognostic relevance of TWA in patients following a dual-chamber (DDD) pacemaker implantation. METHODS Sixty-three patients (mean age 68 ± 13 years) with structural heart disease and recently implanted DDD pacemakers were enrolled. Left ventricular (LV) function was normal or moderately impaired (mean LV ejection fraction 61 ± 13%). All patients underwent sequential TWA testing using atrial and ventricular pacing. RESULTS During atrial pacing requiring physiologic conduction to the ventricles, 21% of TWA tests were positive, 43% negative, and 36% indeterminate. When using right ventricular (RV) pacing in the same patients, 19% of tests were positive, 40% negative, and 41% indeterminate. When positive and indeterminate tests were grouped as nonnegative, the concordance between atrial and ventricular pacing was 62% (κ= 0.22). After a mean follow-up of 5.9 ± 1.9 years, 18 (29%) patients had died. Improved survival was predicted by a negative TWA test using atrial pacing (P = 0.028), but not with ventricular pacing (P = 0.722). CONCLUSIONS In patients with dual-chamber pacemakers, there is a low concordance of TWA test results between atrial pacing with intrinsic conduction to the ventricles and apical RV pacing via pacemaker electrode. However, TWA during atrial pacing clearly exerts long-term prognostic relevance in a patient group with preserved LV function and structural heart disease.
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Affiliation(s)
- Marc Dorenkamp
- Department of Cardiology and Pneumology, Heart Center, Georg-August-University of Göttingen, Göttingen, Germany.
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Burattini L, Bini S, Burattini R. Automatic microvolt T-wave alternans identification in relation to ECG interferences surviving preprocessing. Med Eng Phys 2011; 33:17-30. [PMID: 20920875 DOI: 10.1016/j.medengphy.2010.08.014] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2010] [Revised: 08/10/2010] [Accepted: 08/25/2010] [Indexed: 10/19/2022]
Abstract
The aim was to investigate the effect of interferences surviving preprocessing (residual noise, baseline wanderings, respiration modulation, replaced beats, missed beats and T-waves misalignment) on automatic identification of T-wave alternans (TWA), an ECG index of risk for sudden cardiac death. The procedures denominated fast-Fourier-transform spectral method (FFTSM), complex-demodulation method (CDM), modified-moving-average method (MMAM), Laplacian-likelihood-ratio method (LLRM), and adaptive-match-filter method (AMFM) were applied to interferences-corrupted synthetic ECG tracings and Holter ECG recordings from control-healthy subjects (CH-group; n=25) and acute-myocardial-infarction patients (AMI group; n=25). The presence of interferences in simulated data caused detection of false-positive TWA by all techniques but the FFTSM and AMFM. Clinical applications evidenced a discrepancy in that the FFTSM and LLRM detected no more than one TWA case in each population, whereas the CDM, MMAM, and AMFM detected TWA in all CH-subjects and AMI-patients, with significantly lower TWA amplitude in the former group. Because the AMFM is not prone to false-positive TWA detections, the latter finding suggests TWA as a phenomenon having continuously changing amplitude from physiological to pathological conditions. Only occasional detection of TWA by the FFTSM and LLRM in clinics can be ascribed to their limited ability in identifying TWA in the presence of interferences surviving preprocessing.
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Affiliation(s)
- Laura Burattini
- Department of Biomedical, Electronics and Telecommunication Engineering, Polytechnic University of Marche, Via Brecce Bianche, 60131 Ancona, Italy
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Weiss EH, Merchant FM, d'Avila A, Foley L, Reddy VY, Singh JP, Mela T, Ruskin JN, Armoundas AA. A novel lead configuration for optimal spatio-temporal detection of intracardiac repolarization alternans. Circ Arrhythm Electrophysiol 2011; 4:407-17. [PMID: 21430127 DOI: 10.1161/circep.109.934208] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
BACKGROUND Electric alternans is a pattern of variation in the shape of ECG waveform that occurs every other beat. In humans, alternation in ventricular repolarization, known as repolarization alternans (RA), has been associated with increased vulnerability to ventricular tachycardia/fibrillation and sudden cardiac death. METHODS AND RESULTS This study investigates the spatio-temporal variability of intracardiac RA and its relationship to body surface RA in an acute myocardial ischemia model in swine. We developed a real-time multichannel repolarization signal acquisition, display, and analysis system to record ECG signals from catheters in the right ventricle, coronary sinus, left ventricle, and epicardial surface before and after circumflex coronary artery balloon occlusion. We found that RA is detectable within 4 minutes after the onset ischemia and is most prominently seen during the first half of the repolarization interval. Ischemia-induced RA was detectable on unipolar and bipolar leads (both in near- and far-field configurations) and on body surface leads. Far-field bipolar intracardiac leads were more sensitive for RA detection than body surface leads, with the probability of body surface RA detection increasing as the number of intracardiac leads detecting RA increased, approaching 100% when at least three intracardiac leads detected RA. We developed a novel, clinically applicable intracardiac lead system based on a triangular arrangement of leads spanning the right ventricular and coronary sinus catheters, which provided the highest sensitivity for intracardiac RA detection when compared with any other far-field bipolar sensing configurations. CONCLUSIONS In conclusion, intracardiac alternans, a complex spatio-temporal phenomenon associated with arrhythmia susceptibility and sudden cardiac death, can be reliably detected through a novel triangular right ventricular-coronary sinus lead configuration.
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Affiliation(s)
- Eric H Weiss
- Harvard-MIT Division of Health Sciences and Technology, Massachusetts Institute of Technology, Cambridge, USA
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Chan PS, Gold MR, Nallamothu BK. Do Beta-blockers impact microvolt T-wave alternans testing in patients at risk for ventricular arrhythmias? A meta-analysis. J Cardiovasc Electrophysiol 2011; 21:1009-14. [PMID: 20384655 DOI: 10.1111/j.1540-8167.2010.01757.x] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
INTRODUCTION Results of microvolt T-wave alternans (MTWA) studies vary and may be influenced by whether beta-blocker therapy was withheld prior to MTWA assessment. We conducted a meta-analysis of the predictive value of MTWA screening for ventricular arrhythmic events in primary prevention patients with left ventricular dysfunction and examined whether results differed depending upon whether beta-blocker use was withheld prior to MTWA testing. METHODS AND RESULTS Prospective studies that evaluated whether MTWA predicted ventricular arrhythmic events published between January 1980 and September 2008 were identified. Summary estimates for the predictive value of MTWA were derived with random-effects models. Nine studies involving 3,939 patients were identified. Overall, an abnormal MTWA (positive and indeterminate) test was associated with an almost 2-fold increased risk for arrhythmic events (pooled RR = 1.95, 95% CI: 1.29-2.96; P = 0.002). However, significant heterogeneity across studies was observed (P = 0.024). In the 4 studies in which beta-blocker therapy was not withheld prior to MTWA assessment, an abnormal MTWA test was associated with a 5-fold increased risk for arrhythmic events (pooled RR = 5.39, 95% CI: 2.68-10.84; P < 0.001) and was robust to sensitivity analyses. In contrast, the association was much weaker in those studies where the use of beta-blocker therapy was withheld prior to MTWA testing (pooled RR = 1.40, 95% CI: 1.06-1.84; P = 0.02). CONCLUSIONS In primary prevention patients with left ventricular dysfunction, the predictive power of MTWA varied widely, based on whether beta-blocker therapy was withheld prior to its assessment. This observation may explain the inconsistent results of MTWA studies in this population.
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Affiliation(s)
- Paul S Chan
- Mid-America Heart Institute, Kansas City, MO 64111, USA.
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Burattini L, Zareba W, Burattini R. Identification of gender-related normality regions for T-wave alternans. Ann Noninvasive Electrocardiol 2011; 15:328-36. [PMID: 20946555 DOI: 10.1111/j.1542-474x.2010.00388.x] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/01/2022] Open
Abstract
BACKGROUND T-wave alternans (TWA), a harbinger of sudden cardiac death, associates to a broad variety of pathologies. In a previous study, we observed the presence of unstable and low-amplitude TWA also in healthy subjects, and considered it as "physiological TWA." The possible existence of different TWA characteristics between males and female is investigated in the present work. METHODS Resting ECG recordings from 142 control healthy subjects, 77 males and 65 females, were submitted to our adaptive match filter (AMF) based method for TWA detection and characterization in terms of duration, amplitude, and their product. The 99.5th percentile of these parameters distributions over the entire control population and over the male and female subgroups, were used to define thresholds which delimit a gender-independent and male- and female-related TWA normality regions, respectively, out of which abnormal TWA cases (TWA+) are expected to fall. Clinical usefulness of these regions was tested using a population of 151 coronary artery disease (CAD) patients, divided into 128 males and 23 females. RESULTS In our control-female population, TWA duration was significantly longer than in control-male population (65 ± 13 beat vs 52 ± 14 beat; P < 10(-6) ). Our gender-related normality regions allowed identification of 36 (23.8%) TWA+ cases among the CAD patients, 17 more than those obtained from a gender-independent region. All these 17 patients were CAD males with over-threshold TWA duration. CONCLUSIONS TWA is a gender-related phenomenon. Definition of gender-related TWA normality regions improves identification of patients at increased TWA stability (i.e., prolonged TWA duration) and, thus, at increased risk of arrhythmic events.
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Affiliation(s)
- Laura Burattini
- Department of Biomedical, Electronics and Telecommunication Engineering, Polytechnic University of Marche, Ancona, Italy.
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