Improved survival after heart transplantation in patients bridged with extracorporeal membrane oxygenation in the new allocation system

Abstract

Background: Historically, patients bridged on extracorporeal membrane oxygenation (ECMO) to heart transplantation (HT) have very high post-transplant mortality. In the new heart transplant allocation system, ECMO-supported patients have the highest priority for HT. However, data are lacking on the outcomes of these critically ill patients. We compared the waitlist and post-transplant outcomes of ECMO-supported patients in the new and old allocation systems.

Methods: Adult patients supported by ECMO at the time of listing or transplantation who were registered in the United Network for Organ Sharing database between November 1, 2015 and September 30, 2019 were included. Clinical characteristics, outcomes in the waitlist, and post-transplant survival were compared between the old and new systems. Cox Proportional and subdistribution hazard regression models were used to evaluate the variables contributing to the post-transplant and waitlist outcomes RESULTS: A total of 296 ECMO-supported patients were listed for HT. Of these, 191 were distributed to the old system, and 105 were distributed to the new system. Patients listed in the new system had a higher cumulative incidence of HT (p < 0.001) and lower incidence of death or removal (p = 0.001) from the transplant list than patients listed in the old system. The 6-month survival after transplantation was 74.6% and 90.6% for the old- and new-era patients, respectively (p = 0.002). Among ECMO-supported patients, being listed or transplanted on the new system was independently associated with improved outcomes in the waitlist and after transplantation.

Conclusions: With the implementation of the new heart transplant allocation system, ECMO-supported patients have a shorter waitlist time, improved frequency of HT, and improved short-term post-transplant survival.

Keywords: allocation system; cardiogenic shock; extracorporeal membrane oxygenation; heart transplant; mechanical circulatory support.