BACKGROUND: Duchenne muscular dystrophy (DMD) is frequently complicated by development of a cardiomyopathy. Despite significant medical advances provided to DMD patients over the past 2 decades, there remains a group of DMD patients who die prematurely. The current study sought to identify a set of prognostic factors that portend a worse outcome among adult DMD patients. METHODS AND RESULTS: A retrospective cohort of 43 consecutive patients was followed in the adult UT Southwestern Neuromuscular Cardiomyopathy Clinic. Clinical data were abstracted from the electronic medical record to generate baseline characteristics. The population was stratified by survival to time of analysis and compared with characteristics associated with death. The DMD population was in the early 20s, with median follow-up times over 2 years. All the patients had developed a cardiomyopathy, with the majority of the patients on angiotensin-converting enzyme inhibitors (86%) and steroids (56%), but few other guideline-directed heart failure medications. Comparison between the nonsurviving and surviving cohorts found several poor prognostic factors, including lower body mass index (17.3 [14.8-19.3] versus 25.8 [20.8-29.1] kg/m2, P<0.01), alanine aminotransferase levels (26 [18-42] versus 53 [37-81] units/L, P=0.001), maximum inspiratory pressures (13 [0-30] versus 33 [25-40] cmH2O, P=0.03), and elevated cardiac biomarkers (N-terminal pro-brain natriuretic peptide: 288 [72-1632] versus 35 [21-135] pg/mL, P=0.03]. CONCLUSIONS: The findings demonstrate a DMD population with a high burden of cardiomyopathy. The nonsurviving cohort was comparatively underweight, and had worse respiratory profiles and elevated cardiac biomarkers. Collectively, these factors highlight a high-risk cardiovascular population with a worse prognosis.