Mitigating the impact of using female donor hearts in male recipients using BMI difference.

Abstract Background Heart transplantation is limited by the supply of donor organs. Previous studies have associated female donor to male recipient with decreased post-transplant survival. We wanted to evaluate whether this risk can be mitigated using higher donor than recipient body mass index. Methods We performed a retrospective analysis of the OPTN/UNOS registry encompassing years 2005 to 2018 for all male adult recipients (>18 years) who underwent isolated heart transplantation with grafts from female donors. The association between donor/recipient BMI difference and recipient survival was evaluated using adjusted Cox Proportional Hazards modeling. Results A total of 3,788 male recipients who received female donor hearts met inclusion criteria for analysis. Maximally selected rank statistics identified donor minus recipient BMI of 1.5 as a meaningful cutoff point in the analysis of recipient survival. Multivariable Cox proportional hazards analysis demonstrated that increasing donor BMI relative to recipient BMI up to this cutoff point was associated with improved survival (HR 0.87 per 5-unit difference, 95% CI 0.77-0.99). Above this cutoff point, increasing donor BMI relative to the recipient did not improve survival more than what was achieved by adding 1.5 of BMI difference (HR 0.97 per 5 unit difference, 95% CI 0.90-1.04). Conclusions Increasing donor BMI relative to recipient BMI up to 1.5 units greater than recipient BMI was associated with improved survival. BMI difference may be useful as a simple to calculate surrogate for predicted heart mass difference to help mitigate the impact of sex mismatch in heart transplantation.