Analysis of the revised heart allocation policy and the influence of increased mechanical circulatory support on survival

Objectives: In 2018, the new United Network for Organ Sharing heart allocation policy took effect. This study evaluated waitlist mortality, mechanical circulatory support utilization, and its influence on posttransplant survival.

Methods: Two 12-month cohorts matched for time of year before and after the policy change were defined by inclusion criteria of first-time transplant recipients aged 18 years or older who were listed and underwent transplant during the same era. Student t test and Wilcoxon rank-sum test were used for mean and median differences, respectively. Categorical variables were compared using χ² or Fisher exact test. Kaplan-Meier curves were used to characterize survival, including time-to-event analysis with the log-rank test. Fine-Gray modeling was used to characterize waitlist mortality. Cox proportional-hazard models were used for multivariate analysis.

Results: Waitlist mortality in the new era is significantly improved based on a competing-risks model (Gray test P = .0064). Unadjusted 180-day posttransplant mortality increased from 5.8% during the old era to 8.0% during the new (P = .0134). However, time-to-event analysis showed similar 180-day survival in both eras. After risk adjustment, the hazard ratio for posttransplant 180-day mortality during the new era was 1.18 (95% CI, 0.85-1.64; P = .333). The posttransplant 180-day mortality of the extracorporeal membrane oxygenation bridge-to-transplant subgroup improved from 28.6% in the old era to 8.4% in the new era (P = .0103; log-rank P = .0021). Patients with an intra-aortic balloon pump at the time of transplant had similar 180-day posttransplant mortality between eras (5.4% vs 7.0%; P = .4831).

Conclusions: The United Network for Organ Sharing policy change is associated with reduced waitlist mortality and similar risk adjusted posttransplant 180-day mortality. The new era is also associated with improved 180-day survival in patients undergoing bridge to transplant with extracorporeal membrane oxygenation.