Donor-recipient ethnic mismatching impacts short- and long-term results of heart transplantation

Background: The impact of donor-recipient ethnic matching on heart transplantation (HT) has been poorly studied with inconclusive results. We aimed to investigate the impact of ethnic matching on HT outcomes in Israeli multiethnic patients. Methods: The study comprised 168 patients who underwent HT from 1990-2017. Patients and their donors were ethnically categorized to Jews and Arabs. Primary end points were all-cause in-hospital and late mortality; secondary end points included primary graft dysfunction (PGD), rejections, and vasculopathy. Results: Donor-recipient ethnic matching was found in 111 patients, while 57 were ethnically mismatched. Baseline characteristics were similar in both groups. Ethnic mismatching was associated with >7-fold (P = 0.018) increased risk for in-hospital mortality and >8-fold (P < 0.001) increased risk for PGD. Kaplan-Meier survival analysis showed that overall survival at 10 years was significantly higher among matched patients (73% vs 43%, log-rank P < 0.001). Multivariate analysis showed that ethnic mismatching was associated with an approximately fourfold higher risk for death (P < 0.01). These findings were validated by propensity score analysis. The ethnic mismatched group experienced significantly higher rejection rates compared with the matched group with lower survival free of rejections (log-rank P = 0.029). No differences in vasculopathy were found. Conclusions: Donor-recipient ethnic mismatch is an important independent predictor of early- and long-term outcomes following HT, and is associated with increased risk for PGD, rejections, and mortality. These findings will help to design tailored treatment protocols leading to improved outcomes after HT.