Should Underweight Donors Be Routinely Procured for Heart Transplantation: A Propensity-Matched Cohort Study

Objective: The impact of underweight or low-BMI donors on heart transplantation (HTx) outcomes remains poorly understood. This study aims to investigate the effect of underweight donors on post-transplant outcomes. Methods: We retrospectively analyzed 574 patients divided into 2 groups based on donor BMI: underweight donors (BMI < 20 kg/m², n = 101, 17.6%) and normal-weight donors (BMI 20-25 kg/m², n = 473, 82.4%). Baseline variables and postoperative outcomes were compared using the Student's t-test for continuous variables and the chi-squared test for categorical variables. Propensity score matching (PSM) was performed to balance baseline differences and control for confounders. Survival analysis was performed using the Kaplan-Meier method. Results: The matched cohort included 71 patients per group, with balanced baseline characteristics. Compared to the normal-weight group, recipients of underweight donors had significantly higher rates of respiratory complications (64.8% vs. 47.9%, p = 0.042), neurological complications (15.9% vs. 4.2%, p = 0.021), renal complications (17.4% vs. 5.6%, p = 0.029), and longer postoperative hospital stay (37.2 vs. 28.4 days, p < 0.001). No significant difference was observed in hospital mortality (2.8 vs. 4.2%, p = 0.649). The overall follow-up time was 72.2 ± 1.9 months (range 68.5 to 75.8). The 1-, 3-, and 5-year survival rates for the underweight and normal-weight donor BMI groups were 83.1% vs. 85.9% (p = 0.624), 75.6% vs. 80.2% (p = 0.527), and 72.0% vs. 77.3% (p = 0.468), respectively. Conclusions: Patients receiving hearts from underweight donors demonstrate comparable long-term survival to those from normal-weight donors but have a higher risk of postoperative complications. These findings suggest that underweight donors could be cautiously utilized to expand the donor pool, offering lifesaving opportunities to recipients who might otherwise experience adverse outcomes due to donor scarcity, albeit with an increased risk of postoperative complications.