Australian outcomes from heart transplantation in the machine perfusion era

Background: In the current era of heart transplantation, machine perfusion strategies are emerging as potential additions to the armamentarium of a transplant unit. Donation after circulatory death (DCD) donor hearts assessed through normothermic machine perfusion (NMP) has helped expand the donor pool. Hypothermic machine perfusion (HMP) is emerging as an alternative strategy to traditional static cold storage (SCS) when a prolonged ischemic time is anticipated in brain dead (BD) donors, this is important in Australia where long distant procurement is vital. In this study we examine the outcomes in our unit where both forms of machine perfusion (NMP and HMP), as well as SCS is utilized for donor heart preservation, with a particular focus on severe primary graft dysfunction (sPGD) and mortality.
Methods: 2021 represents the year when both forms of machine perfusion were available to our unit. Heart transplants in our unit from January 2021 to February 2024 were categorized into three groups for retrospective analysis: (I) DCD-NMP group (n=44); (II) BD-HMP group (n=38), and (III) BD-SCS group (n=78).
Results: There were no significant differences in the mean donor and recipient ages between the three groups. Donor preservation time in the BD-HMP group was significantly longer than the donor ischemic time in the BD-SCS group, and organ care system (OCS) run time in the DCD-NMP group (361±89 vs. 208±47 and 249±49 min respectively, P<0.001). For DCD-NMP, BD-HMP and BD-SCS groups respectively: 30-day survival was: 100%, 97% and 100%; 1-year survival was: 94%, 90% and 94%; 2-year survival was: 90%, 90% and 89% (P=0.9). There was no significant difference in the incidence of sPGD between the three groups (DCD-NMP: 7%, BD-HMP: 5%, and BD-SCS: 5%, P=0.9)
Conclusions: Machine perfusion strategies represent important additions to the modern transplant unit and can expand the donor pool. Results are encouraging with no differences in 2-year survival or incidence of sPGD across the preservation modalities: DCD-NMP, BD-HMP, and BD-SCS.