Simultaneous Heart-Kidney Transplant Outcomes Pre- and Post-Heart Allocation System Change: Impact of Temporary Mechanical Circulatory Support

Abstract

<h3>Purpose</h3> The United Network for Organ Sharing (UNOS) changed the donor heart allocation system in October 2018 aiming to prioritize organ availability to candidates with the highest mortality risk. Following this change, the use of temporary mechanical circulatory support devices (tMCS) increased dramatically in transplant centers across the United States. However, the potential effect of this change remains unknown in patients undergoing simultaneous heart-kidney (SHK) transplantation. The aim of this study was to compare outcomes in SHK recipients before and after the allocation change. <h3>Methods</h3> We identified all SHK recipients from the Scientific Registry of Transplant Recipients who underwent transplantation between January 2016 and November 2019. Patients were stratified into pre- and post-heart allocation change groups based on the date of surgery. Kaplan-Meier curves were generated to compare 1-year outcomes by era. Subsequently, patients with the following tMCS devices were identified within each group: Intra-aortic balloon pump (IABP); Impella 2.5, CP, 5.0; Centrimag and VA-ECMO. Separate 1-year survival analyses were performed and compared between pre- and post-heart allocation change. <h3>Results</h3> We identified 400 and 138 patients who underwent SHK transplant pre- and post-heart allocation change, respectively. The overall 1-year survival rate of SHK recipients was lower after October 2018 (p=0.002; Figure 1A). 56 patients (14.1%) were transplanted with a tMCS device before and 65 (47.1%) after the allocation change. There was no significant difference in 1-year survival between the two groups (p=0.319; Figure 1B). <h3>Conclusion</h3> tMCS device use increased following the heart allocation change. Our results indicate that the one-year survival of SHK recipients has declined after the change, but it was independent of the increased tMCS device use. Further studies are needed to evaluate long-term outcomes.