Impact of Heart Transplant Allocation Changes on Waitlist Mortality and Clinical Practice in Pediatric and Adult Patients With Congenital Heart Disease and Cardiomyopathy.

Background: The United Network of Organ Sharing made changes to the priority for allocation of hearts for transplantation (HT) in 2016 for pediatric patients and 2018 for adult patients. Although recent work has evaluated the impact of the revised allocation systems on mechanical circulatory support practices and waitlist outcomes, there are limited data that focus more specifically on the impact of the allocation changes on patients with congenital heart disease (CHD) or cardiomyopathy and how these relationships might differ in pediatric and adult patients.

Methods: The United Network of Organ Sharing database was queried for pediatric (<18 years of age) and adult (18-50 years of age) patients with a CHD or cardiomyopathy diagnosis listed for HT. Cohorts were grouped into preallocation and postallocation change eras: pediatric patients from January 1, 2011, to March 21, 2016, and January 1, 2017, to December 31, 2021; and adult patients from January 1, 2015, to October 17, 2018, and January 1, 2019, to December 31, 2021. Differences in era for survival or waitlist removal because of clinical deterioration from the time of HT listing were compared using competing risk models.

Results: We identified 11 637 patients listed for HT during the study period, including 2882 pediatric patients with CHD, 594 adults with CHD, 2348 pediatric patients with cardiomyopathy, and 5813 adults with cardiomyopathy. In a competing risk model adjusting for demographic and clinical factors, allocation changes were significantly associated with lower death or waitlist removal within 1 year of HT listing in infants with CHD (HR, 0.75 [0.57-0.99]; P=0.04), children with CHD (HR, 0.61 [0.43-0.86]; P=0.005), and adults with cardiomyopathy (HR, 0.60 [0.44-0.81]; P=0.001), but not in infants with cardiomyopathy, children with cardiomyopathy, or adults with CHD.

Conclusions: The recent allocation changes of the Organ Procurement and Transplantation Network associations with waitlist duration and outcome were not uniform across pediatric and adult cohorts with CHD or those with cardiomyopathy. Children with cardiomyopathy and adults with CHD did not experience the mortality benefits experienced by adults with cardiomyopathy and children with CHD. Future iterations of the allocation systems should consider differential access to mechanical circulatory support options for children and adults, patient sensitization status, and whether having separate systems for adults and children is the most appropriate method to allocate organs.