Matchmaking Just Got Easier: Impact of Phenotypic Donor-Recipient Likeness in Heart Transplantation

Phenotypic matching in heart transplantation, where donors and recipients are matched based on physical characteristics, has been previously limited to only analyzing individual variables such as sex and age. This study examines the effects of phenotypic matching utilizing multiple factors simultaneously. Adult patients undergoing heart transplantation between 2006 and 2016 were identified from the Organ Procurement and Transplantation Network database. Phenotypic matching was defined based on six factors: body mass index difference >30%, age difference >30%, height difference >7%, non-identical ABO blood grouping, race, and sex. A value between 0 and 1 mismatched characteristics was considered phenotypically like matching, whereas 2-6 mismatches was considered phenotypically unlike matching. The primary study endpoint was 1-year survival. Risk-adjusted mortality was examined with multivariable Cox regression models. During the study period, 20,052 adult patients underwent heart transplantation, of whom 9595 (47.9%) were phenotypically like and 10,457 (52.1%) were phenotypically unlike matched. No differences in 1-year survival were seen between like and unlike matched patients (risk-adjusted odds ratio 1.05, 95% confidence interval 0.96-1.15, P = .305) after controlling for clinically relevant covariates. Subgroup analyses did not demonstrate survival differences after stratification based on hospital transplant volume and initial waitlist status. Phenotypically like matched patients had longer waiting times compared with unlike matched patients overall (225 days vs 192 days, P < .001). Waiting for a phenotypically matched heart provides no survival benefit and exposes patients to prolonged waitlist times. These findings challenge the notion that a perfect donor heart exists, when in fact this concept may be a misnomer.