Impact of Predicted Heart Mass–Based Donor-Recipient Size Matching on Transplant Outcomes

Background: Currently, guidelines for appropriate donor sizing in recipients mostly focuses on donor–recipient body weight matching. The purpose is to retrospectively determine the impact of predicted heart mass (pHM)–based size matching on heart transplant (HT) outcomes. Methods: According to our institutional registry, 512 consecutive adult patients underwent HT between January 2000 and August 2020. For each patient, pHM and donor-recipient pHM ratio were calculated. Patients were partitioned into quintiles in terms of pHM ratio: undersizing 2, undersizing 1, reference, oversizing 1, and oversizing 2, with mean pHM donor–recipient ratio of 0.81, 0.96, 1.04, 1.12, and 1.28, respectively. Severe early graft failure and 30-day, 90-day, 1-year, and 10-year mortality were analyzed as outcomes. Results: Recipients of the most oversized group were mostly female (P < .001), had higher preoperative pulmonary vascular resistance (P = .009), had higher rate of mechanical circulatory support (P < .05), and showed a lower United Network for Organ Sharing score (P = .041); the respective donors were younger and more frequently male (P = .001). Ischemic time was similar in all groups (P = .358). Pulmonary vascular resistance (P = .023; odds ratio [OR], 2.38), preoperative mechanical circulatory support (P = .05; OR, 3.06), and United Network for Organ Sharing score (P = .033; OR, 1.76) were identified as risk factors for early mortality. Donor-recipient pHM ratio did not impact early graft failure (P = .871) and early mortality (P = .526). Survival analysis after adjustment for pHM ratio subgroups did not show any difference in outcomes. Conclusions: A wide range of pHM ratios seems to be safe. A careful allocation of organs, by considering a pHM ratio mismatch, may balance rescue preoperative clinical profiles and preserve HT outcomes.