BACKGROUND: Durable ventricular assist devices (VADs) are increasingly used to treat children with heart failure. Studies demonstrate worse outcomes for those in cardiogenic shock at the time of VAD, but limited data exist on less acutely ill children. We describe the association between illness severity and outcomes in this population. METHODS: Data were analyzed from 373 children (aged <19 years) receiving durable VADs from 46 centers in the Pediatric Interagency Registry for Mechanical Circulatory Support. Outcomes were compared by Interagency Registry for Mechanical Circulatory Support (INTERMACS) Patient Profile (PP) and pre-implant characteristics using competing risks methodology. RESULTS: Analyses identified 97 patients in cardiogenic shock (PP 1), 222 with progressive decline (PP 2), and 42 stable on inotropes (PP 3). There were 39 infants, 124 were aged 1 to 9 years and 210 were aged 10 to 19 years. A majority had cardiomyopathy and 66 had congenital heart disease (CHD). There were 224 (62%) continuous-flow VADs. Before implant, 40% received mechanical ventilation (MV). Within 6 months post-implant, 57% underwent transplant and 14% died. PP 1 mortality was highest (25% vs 10% for PP 2, hazard ratio [HR]: 2.5, 95% CI: 1.4-4.4, p = 0.02). In PP 1, CHD was an independent mortality risk factor (HR: 2.9, 95% CI: 1.1-7.8, p = 0.03). In PP 2, pulsatile VADs were associated with death (HR: 3.9, 95% CI: 1.6-9.5, p = 0.003). Patients on MV had high mortality (20%-30%) across PP 1 to PP 3 (HR: 3.0 vs no MV, p < 0.001). CONCLUSIONS: Children in shock at the time of VAD implant have poor outcomes. MV is associated with increased mortality even in lower acuity INTERMACS profiles. Further study is needed to identify modifiable risk factors in this population.