Case Report: When cardiomyopathy is the clue: late-presenting propionic acidemia manifesting as acute heart failure

Background Propionic acidemia (PA) is a rare inborn error of metabolism that typically presents in infancy; however, late-onset variants may manifest with atypical features, including cardiac involvement. Dilated cardiomyopathy (DCM) is an uncommon but serious complication. Case summary A 15-year-old with no prior medical history but a significant maternal family history of cardiomyopathy of unknown etiology from an Amish background presented with altered mental status, increased work of breathing, and progressive edema in the context of preceding viral illness. Evaluation revealed severe biventricular dysfunction, chamber dilation, and findings consistent with chronic DCM. Despite supportive management, her course was complicated by ventricular arrhythmias and clinical deterioration. Metabolic workup demonstrated elevated propionylcarnitine and increased urinary 2-methylcitric acid, confirming late-onset variant PA. She was treated with intravenous carnitine and a specialized metabolic formula; however, cardiac function remained severely impaired. In accordance with family wishes, she was discharged home on hospice care. Conclusion Late-onset PA can present as isolated cardiomyopathy in adolescence. Early consideration of metabolic etiologies is essential in unexplained DCM, particularly in high-risk populations.