Mitigation of Post-Transplant Mortality Risk by Appropriate Donor-to-Recipient Size Matching Using Predicted Heart Mass

Abstract

<h3>Purpose</h3> Obesity is a known risk factor for post-transplant mortality. Obesity epidemic in U.S. has led to a higher prevalence of obese patients as potential heart transplant recipients. It is unclear if appropriate size matching of donor-to-recipient using predicted heart mass (PHM) can mitigate this risk among obese recipients. <h3>Methods</h3> We selected all recipients with heart transplants performed between 1995 and 2020 (n=34,812) using the United Network for Organ Sharing database to examine the risk of death in 6 separate categories of recipient's BMI (Table) according to PHM matching. PHM-based appropriate match happened when Donor PHM/Recipient PHM x 100% was within 86% to 114% whereas under- and over-match were defined as <86% and >114%, respectively. Multivariable Cox regression models were created examining long-term risk of death in appropriately matched and over-matched categories compared to under-matched category in the overall cohort and separately within each BMI group. <h3>Results</h3> Upon follow-up (mean 5.29 years), 9,810 patients died. Recipients appropriately matched to donor hearts had an 8% lower risk of death compared to recipients matched with underweight donors by PHM (Table). Compared to those who had under-matched hearts, normal or overweight recipients who received appropriately matched donor hearts based on PHM had a 10-13% lower risk of death post-transplant (Table). In addition, morbidly obese recipients who were appropriately matched with donor hearts also had a 17% lower risk of death post-transplant (borderline statistically significant p=0.06; Table). The risk of death among obese or severely obese recipients did not differ with appropriate PHM matching or over matching compared to under-matching. <h3>Conclusion</h3> Although pretransplant obesity continues to be a risk factor for death post-transplant, appropriate size matching for donor hearts by PHM may lower the risk of death compared to under-matching specifically among normal and overweight recipients.