Cardiomyopathies are diseases of the heart muscle that can cause cardiac dysfunction. The main types include dilated cardiomyopathy, hypertrophic cardiomyopathy, and restrictive cardiomyopathy. Dilated cardiomyopathy is characterized by ventricular dilation and impaired contraction, with the majority of cases being idiopathic. Etiologies of dilated cardiomyopathy include infectious, inflammatory, toxic, metabolic, inherited, and peripartum causes. Treatment aims to reduce preload and afterload through medications like diuretics, vasodilators, and ACE inhibitors. Prognosis depends on the underlying etiology.