Pathophysiology
Clinical meaning
Dilated cardiomyopathy (DCM) features eccentric ventricular remodeling with chamber dilation and reduced systolic function (EF <40%). Myocyte loss and interstitial fibrosis reduce contractile force. Causes include ischemia (most common), viral myocarditis, alcohol, peripartum, and genetic mutations (titin, lamin A/C). Hypertrophic cardiomyopathy (HCM) involves asymmetric septal hypertrophy from sarcomeric protein mutations (beta-myosin heavy chain, myosin-binding protein C), causing LV outflow tract obstruction (LVOTO) worsened by decreased preload/afterload or increased contractility. Restrictive cardiomyopathy (RCM) results from infiltration (amyloidosis, sarcoidosis, hemochromatosis) or fibrosis causing stiff, non-compliant ventricles with preserved EF but severe diastolic dysfunction. Each type has distinct hemodynamic profiles guiding management.