Outcomes of Donor-Recipient Size Mismatch in Donation After Circulatory Death Heart Transplantation

Prior studies of donor-recipient size mismatch only included donation after brain death heart transplants. Given higher rates of primary graft dysfunction, identifying optimal graft selection factors specific to donation after circulatory death (DCD) is crucial. We assessed outcomes of size mismatch in DCD heart transplants based on predicted heart mass (PHM), height, and weight.

The study cohort consisted of 1631 adult patients from the United Network for Organ Sharing dataset who underwent DCD heart transplant between 12/1/2019 and 6/30/2024. Size mismatch was categorized based on donor/recipient ratio: >15% difference for weight and PHM, and >5% difference for height. The primary outcome was post-transplant mortality. Median follow-up time was 359 days with an interquartile range of 165.2-677.5 days.

Stratification by height mismatch resulted in 257 (15.8%) undersized, 1062 (65.1%) size-matched, and 312 (19.1%) oversized donor-recipient pairs. Multivariable logistic regression analysis found that oversized height was independently associated with a significantly greater risk of in-hospital mortality (OR [95% CI]: 2.106 [1.161, 3.822], p = 0.014), while weight and PHM mismatch remained non-significant. Multivariable Cox regression was also performed for longer term mortality by including all mortality events through time of last follow-up, and again found that oversized height was independently associated with the outcome (HR [95% CI]: 1.737 [1.181, 2.555], p = 0.005) while weight and PHM mismatch were not.

Donor-recipient height oversizing by >5% was associated with a greater risk of early and mid-term mortality after DCD heart transplantation.