National utilization and outcomes of heart transplantation using ex situ machine perfusion

In recent years, machine perfusion (MP) for heart transplantation has been increasingly adopted in the United States. However, pragmatic national studies on the utilization and outcomes of this practice are lacking.

Adult (≥18 years) heart recipients transplanted between October 18, 2018 and September 30, 2023 in the United Network for Organ Sharing database were included. We compared outcomes of MP and non-MP transplants among donation after brain death (DBD) and circulatory death (DCD) donors. We used Cox regression to evaluate survival at 30 days and 1 year post-transplant.

Of 13,500 DBD transplants, 403 (3.0%) utilized MP. Donors of MP vs non-MP grafts were older (34 vs 32 years, p = 0.003) and traveled longer distances to the recipient center (478 vs 228 nautical miles, p < 0.001). Recipients of MP vs non-MP DBD grafts had increased risk of predischarge dialysis (adjusted odds ratio (aOR) 1.33 [95% confidence interval (CI): 1.01-1.75], p = 0.04) and predischarge stroke (aOR 1.66 [95% CI: 1.08-2.55], p = 0.02), but similar hazards of mortality at 30 days (adjusted hazard ratio (aHR) 1.01 [95% CI: 0.54-1.86], p = 0.99) and 1 year (aHR 0.98 [95% CI: 0.66-1.43], p = 0.90). Of 976 DCD transplants, 633 (64.9%) utilized MP. Recipients of MP vs non-MP DCD grafts had similar risks of dialysis (aOR 1.19 [95% CI: 0.82-1.72], p = 0.36) and stroke (aOR 1.68 [95% CI: 0.82-3.49, p = 0.16), and similar hazard of 30-day (aHR 1.62 [95% CI: 0.67-3.94], p = 0.28), and 1-year mortality (aHR 0.91 [95% CI: 0.54-1.54], p = 0.73).

MP use in heart transplantation was associated with favorable outcomes, suggesting it has the potential to increase donor heart utilization, particularly for donors with long projected ischemic times.