Predictors of Nonutilization of Ex Vivo Perfused Donor Heart Allografts.

Despite the development of novel procurement technologies, an imbalance remains between the demand for and the availability of donor hearts. We aimed to identify donor characteristics predictive of nonutilization of hearts supported by ex vivo perfusion. A national database was used to identify ex vivo perfused hearts before September 30, 2023. Donors were stratified into cohorts of "Used" and "Discarded" based on final allocation. Logistic regressions were developed to identify predictors of nonutilization in both the ex vivo and non-ex vivo perfused hearts. Of 1,393 hearts supported with ex vivo perfusion, 154 (11%) were unused. Unused donors were older and had more diabetes and hypertension (p < 0.05). By multivariable logistic regression, reduced ejection fraction (7.10 [3.19-15.77], p < 0.001), coronary artery disease (6.27 [1.15-34.30], p = 0.034), and advanced age (3.25 [2.02-5.21], p < 0.001) were predictors of discard. Elevated body mass and prolonged ischemic times were only predictive of discard in the non-ex vivo perfused cohort. Among procured donor hearts supported by ex vivo perfusion, poor heart function, and donor comorbidities were identified as predictors of nonutilization. Increased appreciation for the role of these variables on post-transplantation outcomes will allow for the development of cost-effective strategies to expand the donor pool.