Reassessing Recipient Mortality Under the New Heart Allocation System: An Updated UNOS Registry Analysis

An early report of recipient heart transplantation outcomes under the new U.S. heart allocation system introduced in late 2018 found a lower post-transplant survival rate compared with that of the prior system.

The aim of this study was to examine recipient survival under the new system by using an updated dataset.

The 2015 to 2019 United Network for Organ Sharing registry was queried for adult heart transplant recipients, stratified according to whether the subjects were listed and underwent transplant before or after October 18, 2018, when the new allocation system was implemented. The association between allocation system and recipient mortality was analyzed by using the Kaplan-Meier method and multivariable Cox proportional hazards regression.

A total of 7,119 recipients met inclusion criteria: 6,004 (84%) and 1,115 (16%) listed and undergoing transplant in the old and new allocation systems, respectively. This registry update included 576 new-system recipients, more than double the amount previously analyzed. Recipients from the new system were more likely to be bridged to transplant with temporary mechanical circulatory support devices instead of durable left ventricular assist devices and had longer graft ischemic times. After adjustment, the new system was not associated with poorer survival on Kaplan-Meier survival analysis (log-rank test; p = 0.075) or multivariable Cox proportional hazards modeling (adjusted hazard ratio: 1.18; 95% confidence interval: 0.90 to 1.55).

The short-term survival of recipients listed and receiving a transplant under the old and new allocation systems seems to be comparable. The modification to the allocation system has resulted in several changes to the clinical profiles of patients undergoing transplants that must be closely monitored in the coming years.