Multicenter evaluation of a national organ sharing policy for highly sensitized patients listed for heart transplantation in Canada.

BACKGROUND: Transplantation of sensitized recipients has been associated with increased risk of post-transplant complications. In 2010, the Canadian Cardiac Transplant Network (CCTN) created a unique status listing for highly sensitized heart transplant candidates. Status 4S listing requires calculated panel-reactive antibody (cPRA) level >80% as the sole listing criteria and enables geographic expansion of the donor pool by providing national access. In this study, we describe patient characteristics and outcomes of those transplanted as Status 4S in Canada.

METHODS: Patients' characteristics and clinical outcomes were retrospectively collected from all 11 adult heart transplant centers in Canada.

RESULTS: Ninety-six patients were listed Status 4S from January 2010 to September 2015. Fifty-two were transplanted as Status 4S. Of these 52 transplants, mean cPRA level was 93.4%, mean age was 47 years, 46% were male, 44% had dilated cardiomyopathy and 17% were re-transplanted for cardiac allograft vasculopathy (CAV). Blood group O comprised 42% and 53% had a left ventricular assist device as a bridge to transplant. Desensitization therapy occurred in 9 patients (17%). Over a mean follow-up period of 28 months (1 week to 5.3 years), 9 patients died (17%). Kaplan-Meier 1-year year survival is 86%. Two patients were treated for antibody-mediated rejection (AMR) in the first year post-transplant and 33% of patients had at least 1 ISHLT Grade ≥2R cellular rejection in the first year. Twenty-nine percent of patients developed de novo door-specific antibodies and demonstrated no correlation with AMR. Freedom from CAV at 1 year is 88.5% and at 5 years is 81.0%. Fifty-two percent of donor hearts originated from outside the recipients' geographic and organ donation organization.

CONCLUSIONS: A national strategy of prioritizing highly sensitized heart transplant recipients has demonstrated effective expansion of the donor pool, acceptable short-term survival, freedom from CAV and low rates of clinically relevant AMR. However, we observed significantly higher rates of cellular rejection and de novo donor-specific antibody development in this population. It is currently unknown whether this will translate into poorer long-term outcome.