Novel model to predict survival in DCD heart transplants: Development of a mortality risk score using UNOS data

Background: While prior studies have compared outcomes between donation after brain death (DBD) and donation after circulatory death (DCD) heart transplants, this study focuses on donor and recipient characteristics influencing survival and develop a risk score exclusively in DCD heart transplants. Methods: We analyzed adult DCD heart transplants in the UNOS database from January 2019 to June 2024. Mortality risk factors were assessed using multivariable Cox proportional hazards regression. The coefficients of the most significant factors were used to develop a mortality risk score. Results: Among 18,014 adult heart transplants, 1453 (8.1%) were DCD recipients. One-, two-, and three-year survival rates were 91.6%, 84.8%, and 80.3%, respectively. Statistically significant factors associated with increased mortality included recipient age >65 (HR=1.62, p=0.025), recipient female sex (HR=1.87, p=0.007), recipient diabetes (HR=1.64, p=0.009), prior cardiac surgery (HR=1.46, p=0.049), donor male sex (HR=1.96, p=0.034), longer ischemic time (HR=1.11 per hour, p=0.014) and CMV mismatch: donor-/recipient+ (HR=2.07, p=0.015); donor+/recipient- (HR=1.84, p=0.041). Though not statistically significant (p>0.05), donor age≥45, donor diabetes, donor cause of death, lung retrieval, recipients' pretransplant dialysis, IV inotropes and mechanical ventilation were also added to the mortality risk score model due to its large effect sizes and clinical relevance. Conclusions: We developed a mortality risk score for DCD heart transplants including 7 recipient factors: age >65, female sex, diabetes, prior cardiac surgery, pretransplant ventilator use, IV inotropes; 7 donor factors: age≥45, male sex, diabetes, ischemic time>4 h, cause of death, lung retrieval and CMV positive in either donors or recipients.