Trends in Use and Early Outcomes of Ex Vivo Machine Perfusion in Heart Transplantation From Donation After Brain Death Donors

Introduction Hearts from donation after brain death (DBD) donors are increasingly older and transported over greater distances, prolonging ischemic times and increasing ischemic injury risks with conventional static cold storage (SCS). Ex vivo machine-perfusion (EVMP) of DBD donor hearts could mitigate these risks, potentially improving outcomes, especially in older donors. However, broader use rates and outcomes of EVMP remain uncertain. Methods In total, 12,363 adult DBD-HTs (11,802 SCS, 561 EVMP) that met study criteria (January 2020-June 2024) were identified in United Network for Organ Sharing. EVMP use and recipient survival at 6 months and 1 year were analyzed, stratified by ischemic time (<4, 4-6, ≥6 hours), including subgroup analysis for older donors (>40 years). Cox hazards regression (Cox-HR), Kaplan-Meier survival, and marginal-effects probabilities were used. Results EVMP use in DBD-HTs increased from 1.39% (January-June 2020) to 10.65% (January-June 2024), with substantial regional variability and few high-volume centers driving most of this use. Compared with DBD-HTs with SCS, DBD-HTs with EVMP had similar mortality risk at 6 months and 1 year (Cox-HR, 1.12; 0.86−1.45; P = .414), despite EVMP hearts being from older donors, transported longer distances, and having longer ischemic times. On stratifying by ischemic time and older donors, although DBD-HTs with SCS had higher 1-year mortality risk (Cox-HR=3.69; 1.81-7.51; P <.001, ischemic-time ≥6 hours) compared with the reference cohort, the increase in mortality was substantially attenuated in DBD-HTs where EVMP was used (Cox-HR, 1.77; 0.87-3.61; P = .115, ischemic time ≥6 hours). Conclusions Adoption of EVMP for donor heart transport in DBD-HTs has steadily increased in the United States, showing comparable survival outcomes to SCS despite older donors and longer ischemic times. Additional studies comparing EVMP with other emerging heart transport technologies are needed.