Impact of Changes in the US Heart Allocation System on Waitlist Mortality and Listing Practices.

PURPOSE: In October 2018, the US changed the donor heart allocation policy from a three-tiered status system to a six-tiered system, with higher priority given to those with temporary mechanical circulatory support. The purpose of the current study was to examine changes in listing practices and waitlist mortality before and after the implementation of the new allocation system.

METHODS: Retrospective analysis was performed of adult patients being listed for heart transplant between May 2018-March 2019 as identified in the UNOS database. Exclusions included multi-organ listing and previous transplant. Patients were grouped by era according to initial list date before or after October 18, 2018. Waitlist survival was censored at 6 months or upon transplant.

RESULTS: During the study period, 3,933 patients were listed, with 2,001 prior to allocation change (Era 1, 50.9%) and 1,932 after allocation change (Era 2, 49.1%). No differences were noted between patients listed in age, gender, diagnosis, dialysis, and mechanical ventilation. ECMO at listing was 2.3% vs. 2.6% in Eras 1 & 2, respectively (p=0.557). IABP at listing was more common in Era 2 (4.4% vs. 8.6%, p<0.001), while VAD use was similar (29.8% vs. 28.9%, p=0.547). In Era 1, 521 (26.0%) patients were listed as status 1A, with 892 (44.6%) patients as status 1B. In Era 2, 55 (2.9%) of patients were listed as new status 1, 270 (14.0%) as new status 2, and 211 (10.9%) as new status 3. A trend towards decreased probability of staying on the waitlist was noted in the Era 2 (Figure, p=0.051). However, when censored for removal from the waitlist for reasons other than transplant, waitlist survival was similar (p=0.791).

CONCLUSION: The new allocation system has led to the listing of more patients with intra-aortic balloon pumps, without changes in temporary mechanical support at listing. The new allocation system is associated with more frequent removal from the waiting list due to reasons other than mortality. Continued examination of outcomes with the new system is warranted.