Abstract 16051: Heart Transplantation With a Positive Crossmatch in Pediatric Recipients is Associated With Increased Mortality in the Current Era: An Analysis of the United Network for Organ Sharing Database

Abstract

Introduction: Congenital heart disease (CHD) patients undergoing heart transplantation (HT) often have anti-HLA antibodies (sensitization), increasing the likelihood of a positive crossmatch and in turn an increased risk of mortality post-HT. The burden of sensitization in pediatric HT recipients and outcomes in such patients in the current era are unknown. Methods: The United Network for Organ Sharing (UNOS) database was queried for patients <18 y/o with CHD undergoing HT between 4/1/2015 and 12/31/2019. Panel reactive antibody (PRA) at HT was collected; patients were grouped into 3 categories: nonsensitized (PRA <10%), moderately sensitized (PRA 10-79%), and highly sensitized (PRA ≥80%). Data regarding crossmatch at HT were collected. One-year post-HT mortality based on sensitization category and crossmatch result were evaluated using multivariable Cox regression. Results: During the study period, 881 CHD patients with PRA data underwent HT; 69% nonsensitized, 22% moderately sensitized, and 9% highly sensitized. Positive crossmatch by flow cytometry or cytotoxicity was more commonly seen in highly sensitized patients (Table 1). Highly sensitized patients had 28% 1-year mortality. After adjustment, both 1-year mortality and graft loss were higher in highly sensitized patients than nonsensitized patients (HR 4, CI 2.4-6.7, P<0.001 and HR 6.8, CI 3.6-12.8, P<0.001, respectively); positive crossmatch by flow cytometry or cytotoxicity was also associated with increased risk of mortality and graft loss (HR 2.1, CI 1.3-3.4, P = 0.002 and HR 3.1, CI 1.7-5.6, P<0.001, respectively). Conclusions: Highly sensitized pediatric CHD patients have 1-year post-HT mortality of nearly 30%, a 4-fold increase compared to nonsensitized patients; positive crossmatch also increased the risk of mortality and graft loss. Due to these poor outcomes, aggressive desensitization as well as alternatives to transplant should be considered in these high-risk patients.