Outcomes of patients receiving extracorporeal membrane oxygenation: Direct vs consultative advanced heart failure and transplant cardiology physicians’ role

Abstract

This manuscript provides a commentary on the article by Zhang et al. Patients with heart and pulmonary failure who do not respond to standard treatment may benefit from extracorporeal membrane oxygenation (ECMO) support. Advanced heart failure and transplant cardiology (AHFTC) teams play an essential role in managing patients in cardiogenic shock. To determine whether ECMO patient management outcomes differ based on whether AHFTC physicians assume a direct or consultative role, a retrospective cohort study of 51 patients placed on veno-venous and veno-arterial (VA) ECMO between January 2015 and February 2023 was conducted. Results demonstrated a significantly higher 30-day post-discharge survival rate in the AHFTC direct involvement cohort compared to the consultative group (67% vs 30%) for all ECMO patients. This survival benefit was primarily attributable to VA ECMO patients (64% vs 20%). Direct involvement of AHFTC teams in patient selection and management may enhance survival in patients requiring VA ECMO for cardiogenic shock; however, further research is necessary to confirm these findings.

Key Words: Advanced heart failure; Critical care; Extracorporeal membrane oxygenation; Mortality; Patients’ outcomes; Physicians’ role; Transplant cardiology; Veno-arterial; Veno-venous

Core Tip: Mortality and morbidity remain substantial among critically ill patients receiving extracorporeal membrane oxygenation (ECMO). Evidence shows that advanced heart failure and transplant cardiology specialists improve outcomes by assuming a direct attending role rather than a solely consultative role. This improvement is especially evident in patients receiving veno-arterial ECMO support.

TO THE EDITOR

Patients with heart failure (HF) often experience symptoms such as fatigue, fluid retention, and dyspnea due to impaired cardiac function[1-3]. Following myocardial infarction, HF remains a leading cause of late morbidity and mortality[4]. Globally, HF affects approximately 64 million individuals[5,6]. Advanced HF (AHF) represents the terminal stage of HF, characterized by persistent and severe symptoms despite guideline-directed medical therapy[7]. Patients with AHF are at increased risk of cardiovascular hospitalization and death, and they typically have a reduced quality of life and functional capacity[8,9]. Heart transplantation remains the gold standard treatment for end-stage HF, although it entails significant perioperative risks and long-term complications[10].

Cardiogenic shock (CS), a state of severe circulatory failure, results in peripheral hypoperfusion, tissue hypoxia, and impaired vascular responsiveness, which can lead to irreversible multisystem organ failure[11,12]. Mechanical circulatory support is often necessary to maintain hemodynamics in CS patients. Many individuals with decompensated HF experiencing severe hemodynamic instability require admission to cardiac intensive care units[13]. AHF and transplant cardiology (AHFTC) teams are critical in managing these patients due to their expertise in advanced cardiac therapies.

Extracorporeal membrane oxygenation (ECMO) is a valuable intervention for patients with heart and pulmonary failure unresponsive to conventional treatment, serving both as a lifesaving measure and as a bridge to more definitive therapies[14]. Veno-arterial (VA) ECMO, which provides the highest level of hemodynamic support, is especially beneficial for patients with severe CS[15]. The use of ECMO in adults with profound cardiac dysfunction is increasing, predominantly driven by growing adoption of VA ECMO[16-18]. However, the use of VA ECMO in elderly patients remains controversial and is considered a relative contraindication in many centers[18-20]. Previous studies have demonstrated that the presence of structured multidisciplinary ECMO teams improves patient outcomes[21-23]. For instance, Dalia et al[22] reported that hospital survival significantly improves with a dedicated multidisciplinary ECMO team. This manuscript aims to underscore the role of AHFTC teams in optimizing ECMO patient outcomes and to highlight the potential benefits of ECMO support in patients with AHF.

DIRECT VS CONSULTATIVE AHFTC PHYSICIANS’ ROLE IN THE OUTCOMES OF ECMO PATIENTS

Patients admitted to cardiac intensive care units have shown improved clinical outcomes when managed directly by AHFTC physicians[24]. In a recent study by Zhang et al[25], 51 patients [26 on VA ECMO and 25 on veno-venous (VV) ECMO] were divided into two groups based on the AHFTC team's role: Direct management vs consultative support. Twenty-one patients received direct AHFTC care, and 30 were managed under a consultative model.

VA ECMO indications included post-cardiotomy shock (10 patients), myocarditis (7 patients), and other causes of CS (9 patients). VV ECMO was used primarily for acute respiratory distress syndrome (19 patients). Although mechanical ventilation needs were high in both cohorts (90%–100%), the proportions requiring Swan-Ganz catheterization and temporary mechanical circulatory support were comparable. However, renal replacement therapy was more frequently employed in the consultative cohort (60% vs 24%).

Comparison of survival outcomes in a cohort of ECMO patients with direct vs consultative AHFTC involvement

Post-decannulation survival rates favored the AHFTC direct cohort, with combined VA ECMO and VV ECMO survival at 71% vs 57% in the consultative group. Survival among VA ECMO patients was 73% vs 60% post-decannulation, and VV ECMO patients showed 70% vs 53%, respectively, though these differences were not statistically significant.

Most notably, 30-day post-discharge survival was significantly greater in the AHFTC direct cohort for both VA ECMO and VV ECMO patients, especially VA ECMO (64% direct vs 20% consultative). The consultative cohort also experienced a higher incidence of post-ECMO decannulation deaths and stroke, with stroke-associated mortality at nearly 89%. These findings highlight the critical importance of direct AHFTC involvement in stroke prevention, optimal timing of ECMO decannulation, and post-ECMO CS management (Figure 1).

Figure 1 Comparison of survival outcomes in a cohort of extracorporeal membrane oxygenation patients with direct vs consultative advanced heart failure and transplant involvement. TSAD: Total survival after decannulation; TSADWCAHFTCR: Total survival after decannulation with consultative advanced heart failure and transplant cardiology role; TSADWDAHFTCR: Total survival after decannulation with direct advanced heart failure and transplant cardiology role; TST30DPD: Total survival to 30 days post discharge; TST30DPDWCAHFTCR: Total survival to 30 days post discharge with consultative advanced heart failure and transplant cardiology role; TST30DPDWDAHFTCR: Total survival to 30 days post discharge with direct advanced heart failure and transplant cardiology role; TVASAD: Total veno-arterial survival after decannulation; TVAST30DPD: Total veno-arterial survival to 30 days post discharge; TVVSAD: Total veno-venous survival after decannulation; TVVST30DPD: Total veno-venous survival to 30 days post discharge; VASADWCAHFTCR: Veno-arterial survival after decannulation with consultative advanced heart failure and transplant cardiology role; VASADWDAHFTCR: Veno-arterial survival after decannulation with direct advanced heart failure and transplant cardiology role; VAST30DPDWCAHFTCR: Veno-arterial survival to 30 days post discharge with consultative advanced heart failure and transplant cardiology role; VAST30DPDWDAHFTCR: Veno-arterial survival to 30 days post discharge with direct advanced heart failure and transplant cardiology role; VVSADWCAHFTCR: Veno-venous survival after decannulation with consultative advanced heart failure and transplant cardiology role; VVSADWDAHFTCR: Veno-venous survival after decannulation with direct advanced heart failure and transplant cardiology role; VVST30DPDWCAHFTCR: Veno-venous survival to 30 days post discharge with consultative advanced heart failure and transplant cardiology role; VVST30DPDWDAHFTCR: Veno-venous survival to 30 days post discharge with direct advanced heart failure and transplant cardiology role.

Future multicenter prospective studies are necessary to validate these findings and develop interdisciplinary standardized training for ECMO providers. Healthcare systems should consider early integration of AHFTC physicians into patient management and decision-making processes regarding ECMO candidacy.

ECMO TECHNIQUES

VV ECMO

VV ECMO is the predominant extracorporeal life support (ECLS) modality for adults with severe refractory respiratory failure. It provides oxygenation without cardiac support by draining deoxygenated blood typically via femoral vein cannulation and reinfusing oxygenated blood through the internal jugular vein. This configuration maintains native cardiac function and offers advantages such as reduced vascular and neurological complications compared to VA ECMO. It is widely utilized as a bridge to lung transplantation[26].

VA ECMO

For individuals experiencing refractory CS, VA ECMO may be utilized. It can be used for respiratory failure or haemodynamic support[27]. Cannulation can be done peripherally, typically through femoral arteries, or centrally, draining from the right atrium and reinfused in the aorta. Recent reports have described the use of bicaval venous cannulation to set up a central VA ECMO in patients with pulmonary arterial hypertension and severe cardiomegaly. This allows for lung implantation without experiencing significant haemodynamic effects during cardiac manipulation and provides the best possible cardiac support[26,28].

VA ECMO can be administered centrally or peripherally, but the central setting offers a number of benefits. For example, it guarantees a higher blood flow by utilising a large inflow cannula with a large outflow cannula, preventing problems associated with peripheral ECMO, such as limb ischaemia, blood flow insufficiency, vessel damage, and groin infection. Peripheral ECMO is less invasive, can be put up under local anesthesia, doesn't require a clamshell incision, and can be kept in place after surgery[26]. Comparison between VV ECMO and VA ECMO (Table 1).

Table 1 Comparison of veno-arterial and veno-venous extracorporeal membrane oxygenation.

Feature	Veno-arterial ECMO	Veno-venous ECMO
Cardiac support	Supports systemic circulation	Does not support systemic circulation
Cannulation	Arterial and venous	Venous only
Pulmonary circulation	Decreases pulmonary artery pressures	Maintains pulmonary circulation
Perfusion rates	Requires lower rates	Requires higher rates
Partial pressure of oxygen in arterial blood	Higher achievable	Lower achievable
ECMO circuit configuration	Connected in parallel to heart and lungs	Connected in series to heart and lungs

ECMO: Extracorporeal membrane oxygenation.

Patients with CS, including post-cardiotomy CS, acutely decompensated HF with reduced ejection fraction, massive pulmonary thromboembolism, cardiac arrest, refractory ventricular tachycardia, and haemodynamic complications from various invasive procedures can be stabilized with VA ECMO, a bridge-to-recovery therapy that is usually started with cannulation of the common femoral artery and vein[29]. VA ECMO can save individuals with refractory CS. If the patient has entirely or substantially healed from the condition that necessitated the use of ECMO, the device may be effectively withdrawn after a few days of mechanical assistance. Between 31% and 76% of patients with refractory CS are effectively weaned off of ECMO[27].

ECMO COMPLICATIONS

Even though ECMO has positive outcomes in many diseases, treatment can have a number of side effects that increase morbidity and death[30]. Increased in-hospital mortality, limb ischaemia, haemolysis, sepsis, and hemorrhagic and thrombotic events are among the consequences linked to prolonged VA ECMO therapy[31]. The most frequent vascular problems associated with cannulation are retroperitoneal haemorrhage, pseudoaneurysm, and arterial dissection, which affect 7%–14% of patients. Even with minor vascular injuries, retroperitoneal bleeding can happen when anticoagulation is present; signs of this condition include a declining hemoglobin level, an elevated lactate level, and a decline in haemodynamics. However, the presence of thrombi in the circuit is linked to poor neurological outcomes including stroke[32,33]. ECLS for postcardiotomy CS is linked to a high rate of complications and death[34]. According to a study, iatrogenic vascular injuries and consequences necessitated consultation with vascular surgery for 23.6% of patients[35].

CONCLUSION

Direct involvement of AHFTC teams in the management of ECMO patients, especially those requiring VA ECMO support, is associated with improved survival, particularly 30 days following hospital discharge. Given the complexities surrounding ECMO management and associated complications, direct AHFTC engagement facilitates optimized patient selection, care coordination, and targeted interventions. Nonetheless, larger prospective studies are needed to confirm these benefits and refine best practice protocols.