Effect of the New Donor Heart Allocation System on Waitlist and Post-Transplant Mortality in Candidates and Recipients with a Durable Left Ventricular Assist Device

Abstract

<h3>Purpose</h3> To evaluate the effect of the new donor heart allocation system on waitlist and post-transplant (HTx) mortality in candidates listed with a durable left ventricular assist device (LVAD). <h3>Methods</h3> The United Network for Organ Sharing (UNOS) database was queried for adults listed for heart transplantation with a durable LVAD between October 2015 and August 2020. Fine-Gray competing risks analysis was utilized to examine the association between implementation of the new donor heart allocation system and removal from the waitlist due to death or worsening clinical condition among candidates listed with a durable LVAD. Post-HTx survival was examined using Kaplan-Meier estimates and Cox proportional hazards analysis. <h3>Results</h3> 3399 (67.3) of the 5052 candidates included in this study were listed under the old system. Listing under the new system provided significant protection from waitlist removal due to death or clinical deterioration within 365 days (HR: 0.70, 95% CI: 0.53-0.91, <i>p</i>=0.01) of listing (Figure A). Of these candidates, HTx recipients under the new system were more likely to experience death or retransplant within 365 days of HTx (HR: 1.84, 95% CI 1.42-2.40, <i>p</i><0.01) (Figure B). Age at and gender distribution at HTx were similar between groups, although those transplanted under the new system had significantly higher body mass index (29.5 vs. 28.6 kg/m², <i>p</i><0.01). Ischemic time under the new system was 3.4 hours (interquartile range (IQR): 2.8-4.1 hours) vs. 3.1 hours (IQR: 2.3-3.7 hours) under the old system (<i>p</i><0.01). The proportion of mechanically ventilated recipients were similar (0.4 vs. 0.4%, <i>p</i>=0.94). <h3>Conclusion</h3> Candidates listed with a durable LVAD experience less waitlist morbidity and mortality under the new system compared to the old system, although post-HTx survival may suffer. This could be representative of wider regional sharing of organs and associated increases in ischemic time.