Sex-Specific Trends in Temporary Mechanical Circulatory Support Use as Bridge to Orthotopic Heart Transplant

Background: Following the United Network for Organ Sharing (UNOS) allocation change, patients listed for orthotopic heart transplant are increasingly bridged with temporary mechanical circulatory support (tMCS); however sex-specific data are limited. Objectives: The authors sought to examine sex-specific trends in tMCS utilization before and after the allocation change. Methods: We retrospectively analyzed UNOS data from October 2015 to June 2023, comparing baseline characteristics, tMCS use, and outcomes between sexes across allocation eras. Multivariable regression was used to identify predictors of tMCS utilization, waitlist, and post-transplant mortality. Results: In the postallocation period, male sex and blood type O were independently associated with tMCS use. Women were more likely bridged with intra-aortic balloon pump (IABP) (67% vs 61% P < 0.001) with shorter waitlist times (13 vs 16 days; P < 0.001). Extracorporeal membrane oxygenation (ECMO) utilization increased for both men (1.1% to 10%) and women (0.5% to 13%). Waitlist death decreased for both sexes; however, women experienced worse 1-year post-transplant survival (P = 0.012). Compared with IABP, nondischargeable/percutaneous left ventricular assist devices (subdistribution HR: 2.2; 95% CI: 1.69-2.88; P < 0.001) and ECMO (subdistribution HR: 5.29; 95% CI: 3.98-7.07; P < 0.001) were associated with higher waitlist death. ECMO was associated with increased risk of post-transplant mortality (P < 0.001). Conclusions: Post allocation change, women remain less likely to be listed on tMCS and more often bridged with IABP. Although waitlist outcomes have improved independent of sex, women experience worse 1-year post-transplant survival. Device type was the strongest predictor of poor outcomes.