AbstractIntroductionThe relationship between donor age and adolescent heart transplant outcomes remains incompletely understood. We aimed to explore the effect of donor‐recipient age difference on survival after adolescent heart transplantation.MethodsThe United Network for Organ Sharing database was used to identify 2,855 adolescents aged 10–17 years undergoing isolated primary heart transplantation from 1/1/2000 to 12/31/2022. The primary outcome was 10‐year post‐transplant survival. Multivariable Cox regression identified predictors of mortality after adjusting for donor and recipient characteristics. A restricted cubic spline assessed the non‐linear association between donor‐recipient age‐difference and the adjusted relative mortality hazard.ResultsThe median donor‐recipient age‐difference was +3 (range ‐13 to +47) years, and 17.7% (n = 504) of recipients had an age‐ difference > 10 years. Recipients with an age‐difference > 10 years had a less favorable pre‐transplant profile, including a higher incidence of priority status 1A (81.6%, n = 411 vs. 73.6%, n = 1730; p = .01). The 10‐year survival rate was 54.6% (95% confidence interval (CI) 48.8– 60.4) among recipients with a donor‐recipient age‐difference > 10 years and 66.9% (95% CI: 64.4–69.4) among those with an age‐difference ≤10 years. An age‐difference > 10 years was an independent predictor of mortality (hazard ratio 1.43, 95% CI: 1.18–1.72, p < .001). Spline analysis demonstrated that the adjusted mortality hazard increased with increasingly positive donor‐recipient age‐difference and became significantly higher at an age‐difference of 11 years.ConclusionA donor‐recipient age‐difference > 11 years is independently associated with higher long‐term mortality after adolescent heart transplantation. This finding may help inform acceptable donor selection practice for adolescent heart transplant candidates.