Diagnosis of Dilated Cardiomyopathy Chest x-ray ECG Echocardiography Cardiac MRI Endomyocardial biopsy (select cases) Testing for cause as indicated Diagnosis of dilated cardiomyopathy is by history, physical examination, and exclusion of other common causes of ventricular failure (eg, systemic hypertension, primary valvular disorders, myocardial infarction —see table Diagnosis and Treatment of Cardiomyopathies).