Correlation between heart rate variability and severity of coronary atherosclerosis: Looking for non-invasive indicators of the disease severity

Table 1 Baseline demographics

Variables		n	%	mean ± SD
Sex	Women	57	41.01
	Men	82	58.99
Age (years)				58.98 ± 9.63
BMI (kg/m2)				27.80 ± 3.71
Gensini score				40.02 ± 56.95
Type 2 diabetes mellitus		30	21.58
Hypertension		102	73.38
Current smoker		49	35.25
Hypercholesterolemia		90	64.75
History of myocardial infarction	Q-wave	40	28.78
	Non-Q wave	1	0.72
CCS classification
CCS I		28	20.1
CCS II		55	39.6
CCS III		38	27.3
CCS IV		18	13
History of TIA		1	0.72
History of stroke		10	7.19
History of CABG		5	3.6
History of PTCA		15	10.79
ASA		139	100
ACE-I usage		92	66.19
Diuretic usage		41	29.5
Calcium-channel blocker usage		24	17.27
Antiarhythmic usage		9	6.47
Statin usage		95	68.35
Fibrate usage		6	4.32
Beta-blocker usage		92	66.19
Nitrate usage		68	48.92

ASA: Acetylsalicylic acid; ACE-I: Angiotensin-converting enzyme inhibitors; BMI: Body mass index; CABG: Coronary artery bypass graft; CCS: Canadian Cardiovascular Society; PTCA: Percutaneous coronary angioplasty; TIA: Transient ischemic atta.

Table 2 Correlation analysis between time-domain heart rate variability indices (traditional and novel) and the severity of coronary atherosclerosis assessed by the Gensini score

HRV indices	Correlation analysis (n = 139)
	r	P value
SDNN	-0.046	NS
RMSSD	0.013	NS
de Hann STI	-0.227	< 0.05
de Hann LTI	-0.087	NS
Yeh DI	-0.131	NS
Yeh II	-0098	NS
Organ BAND	-0.087	NS
van Geijn ID	-0.232	< 0.05
Huey STV	-0.137	NS
Huey LTV	-0.167	< 0.05
Dalton MABB	-0.169	< 0.05
Dalton SD	-0.091	NS
Zugaib STV	-0.142	NS
Zugaib LTV	-0.124	NS

DI: Differential index; HRV: Heart rate variability; ID: Interval difference; II: Interval index; LTI: Long-term irregularity; LTV: Long-term variability; NS: Not significant; r: Spearman’s Rank correlation coefficient; RMSSD: Square root of the mean of the sum of the squares of differences between adjacent NN intervals; SD: Standard deviation; SDNN: Standard deviation of all NN intervals; STI: Short-term irregularity; STV: Short-term variability; Dalton MABB: Dalton mean absolute beat-to-beat.

Table 3 Correlation analysis between spectral heart rate variability indices and the severity of coronary atherosclerosis assessed by the Gensini score

HRV indices	Correlation analysis (n = 139)
	r	P value
TP	-0.091	NS
VLF	0.034	NS
LF	-0.125	NS
HF	-0.11	NS
LF/HF	0.036	NS
AR TP	-0.132	NS
AR VLF	0.12	NS
AR LF	0.032	NS
AR HF	-0.065	NS
AR LF/HF	-0.028	NS

AR HF: High frequency range, autoregressive modeling; AR LF: Low frequency range, autoregressive modeling; AR LF/HF: Ratio LF/HF, autoregressive modeling; AR TP: Total power, autoregressive modeling; AR VLF: Very low frequency range, autoregressive modeling; HF: High frequency; HRV: Heart rate variability; LF: Low frequency; LF/HF: Ratio LF/HF; NS: Not significant; r: Spearman’s Rank correlation coefficient; TP: Total power; VLF: Very low frequency range.

Table 4 Correlation analysis between joint time-frequency domain heart rate variability indices and the severity of coronary atherosclerosis assessed by the Gensini score

HRV indices	Correlation analysis (n = 139)
	r	P value
The Allan factor	-0.06	NS
w1	-0.154	NS
w2	-0.151	NS
w3	-0.1	NS
w4	-0.47	NS
w5	-0.134	NS

HRV: Heart rate variability; NS: Not significant; r: Spearman’s Rank correlation coefficient; w1-w5: Wavelet indices.