Abstract Body (Do not enter title and authors here):
Background
In recent years, both mechanical circulatory support devices (MCSD) and grafts from donation after circulatory death (DCD) are increasingly utilized for patients undergoing heart transplant. Multiple studies have demonstrated no difference in outcomes for DCD recipients compared to donation after brain death (DBD). To date, no study has examined whether outcomes remain similar among patients supported with MCSD pre-transplant.

Methods
Using the United Network for Organ Sharing database, adult patients who underwent single-organ heart transplant from 12/1/2019 to 12/31/2023 were identified. MCSD included extracorporeal membrane oxygenation (ECMO), intra-aortic balloon pump (IABP), Impella, and durable ventricular assist devices (VAD).

Results
Among 12131 patients as defined above, 1059 (8.7%) received DCD and 11072 (91.3%) received DBD grafts. Of these, 557 (52.6%) DCD recipients and 7315 (66.1%) DBD recipients were supported with at least one MCSD pre-transplant. Recipients on ECMO or IABP were more likely to receive DBD grafts, whereas those with durable VADs were more likely to receive DCD grafts (Figure 1). There was no significant difference in DCD vs. DBD selection for patients supported by Impella (4.06% vs. 4.85%, p=0.087).

In the MCSD population, DCD recipients had a 30% increased risk of mortality compared to DBD recipients (95% confidence interval: 1% to 69%; Figure 2). Compared to DBD recipients, DCD recipients had higher rates of new dialysis post-transplant (17.4% vs. 14.0%, p=0.031) and higher rates of re-transplant (1.3% vs. 0.4%, p=0.016). Mean graft left ventricular ejection fraction at 1 year did not differ significantly between DCD vs. DBD recipients (59% vs. 60%, p=0.308).

Conclusions
For patients supported by MCSD pre-transplant, receiving a DCD graft is associated with higher morbidity and mortality. Clinicians should proceed with caution in selecting DCD donors for this population.