Impact of ABO compatibility on outcomes after heart transplantation in a national cohort during the past decade

Background Immunologic incompatibility has implications for primary graft failure, rejection, and survival in heart transplantation. To our knowledge, this is the first large cohort study investigating the impact of ABO-compatible versus identical blood type matching on post heart transplantation survival. Methods We used a nationwide sample (2000-2010) within the United Network for Organ Sharing database. Stratification was between ABO-identical and ABO-compatible heart transplantations for univariate and multivariate analyses. The primary end point was graft failure from all causes. Posttransplant survival was compared between groups using Cox proportional hazard and logistic regression models. Results A total of 17,951 patients met inclusion criteria, and 2684 (approximately 15%) underwent ABO-compatible heart transplantation. ABO-compatible recipients were generally sicker than ABO-identical recipients before transplant because more were status 1A, in the intensive care unit, and receiving mechanical ventilatory support (P <.05). Univariate analysis correlated ABO-compatible transplants with decreased posttransplant survival and a higher incidence of primary graft failure as cause of death (P <.05). There was no significant difference in acute graft rejection (P =.53). Multivariate analysis, however, did not demonstrate adverse outcomes in terms of decreased graft survival (hazard ratio, 0.99; P =.87). Blood type O donor grafts were associated with poorer outcomes compared with all other types (P <.05). Conclusions ABO-compatible transplantation does not result in adverse outcomes with respect to graft survival. Blood type O donor grafts, however, were associated with decreased survival. This has important implications for current graft allocation policies, particularly for type B recipients.