Abstract 17085: The Modified US Heart Allocation System Improves Waitlist Mortality for Patients With Hypertrophic Cardiomyopathy

Abstract

Introduction: On October 18, 2018, the US donor heart allocation policy was restructured to better stratify patients, decrease status exemptions, and improve inequities. Previously, HCM patients experienced significant waitlist mortality and functional decline, often requiring status exemptions to be transplanted. This study aims to examine changes in waitlist mortality and transplant rates of HCM patients in the new system. Methods: Retrospective analysis was performed of the UNOS Transplant Database for all isolated adult single-organ heart transplant patients listed between April 20, 2008 and December 6, 2019. Redo heart transplants were excluded. Patients were grouped by diagnosis (HCM or ICM & NICM) and divided into eras based on allocation system. Era 1 spanned April 20 th , 2008 to October 17 th , 2018 and Era 2 spanned October 18 th , 2018 to December 6 th , 2019. Results: During the study period, 28,930 patients were listed, with 26,354 in Era 1 (750 HCM, 2.8%) and 2,576 in Era 2 (107 HCM, 4.2%). Across eras, no differences in age, ethnicity, gender, dialysis, and mechanical ventilation were noted among HCM patients (p>0.05). ECMO usage for HCM at listing was 1.3% in Era 1 vs 2.8% in Era 2 (p=0.557). Use of bridge-to-transplant LVADs remained low in HCM patients (Era 1: 4.3% vs Era 2: 1.9%, p=0.505). Status upgrades for HCM patients decreased from 49% to 39% (p=0.06). Waitlist survival was improved in Era 2 for HCM patients (Figure 1, p=0.001). Transplant rates trended higher in Era 2 for HCM (Figure 1, p=0.344). Thirty-day mortality post-transplant in HCM patients was 2.36% in Era 1 and 1.47% in Era 2 (p=0.643). Conclusions: The new allocation system has led to significantly increased one-year waitlist survival and a near-significant decrease in status upgrades for HCM patients. Moreover, HCM patients trended towards higher transplant rates and shorter waitlist times in the new system. Continued investigation of listing practices and outcomes of HCM patients is warranted.