Impact of Heart Failure Etiology on Waitlist Mortality in Heart Transplant Candidates Supported With Extracorporeal Membrane Oxygenation

Background

Extracorporeal membrane oxygenation (ECMO) has gained traction as a bridge to heart transplantation (HT) but remains associated with increased waitlist mortality. This study explores whether this risk is modified by underlying heart failure (HF) etiology.

Methods

Using the Organ Procurement and Transplantation Network registry, we conducted a retrospective review of first-time adult HT candidates from 2018 through 2022. Patients were categorized as “ECMO”, if ECMO was utilized during the waitlisting period, or “No ECMO” otherwise. Patients were then stratified according to the following HF etiology: ischemic cardiomyopathy (CMP), dilated nonischemic CMP, restrictive CMP, hypertrophic CMP, and congenital heart disease (CHD). After baseline comparisons, waitlist mortality was characterized for ECMO and HF etiology using the Fine–Gray regression.

Results

A total of 16 143 patients were identified of whom 7.0% (n = 1063) were bridged with ECMO. Compared to No ECMO patients, ECMO patients had shorter waitlist durations (46.3 vs. 185.0 days, p < 0.01) and were more likely to undergo transplantation (75.3% vs. 70.3%, p < 0.01). Outcomes analysis revealed that ECMO was associated with increased mortality risk (subdistribution hazard ratio [SHR]: 3.42, p < 0.01), a risk that persisted in all subgroups and was notably high in CHD (SHR: 4.83, p < 0.01) and hypertrophic CMP (SHR: 9.78, p < 0.01). HF etiology comparison within ECMO patients revealed increased mortality risk with CHD (SHR: 3.22, p < 0.01). Within No ECMO patients, hypertrophic CMP patients had lower mortality risk (SHR: 0.64, p = 0.03).

Conclusions

The increased waitlist mortality risk with ECMO persisted after stratification by HF etiology. These findings can help decision-making surrounding candidacy for cannulation and prognostic evaluation.