Study Cohort
Of the 33,657 patients included in the study, 3,728 (11%) experienced the primary outcome of death within one year (Figure 1 ). The majority of study participants were male (75%) with an average age of 52.8 ±12.4 years. Balancing by primary outcome, patients were randomly split into 80% training cohort and 20% validation cohort. Patient characteristics were similar between cohorts, including age, sex, etiology of heart failure, end-organ function, pre-transplant mechanical circulatory support, and days spent on waiting list (Table 1 ).