Restrictive Cardiomyopathy

Restrictive cardiomyopathy (RCM) is the least common cardiomyopathy, characterized by stiff, non-compliant ventricular walls that restrict diastolic filling while systolic function is preserved (or only mildly reduced). The ventricles cannot relax adequately during diastole, so they cannot fill with sufficient blood, leading to elevated filling pressures, atrial dilation, and signs of heart failure (primarily right-sided: JVD, peripheral edema, hepatomegaly, ascites). Causes include: infiltrative diseases (amyloidosis — most common cause in developed countries, where abnormal amyloid protein deposits in the myocardium making it stiff; sarcoidosis, hemochromatosis — iron deposition), storage diseases (Fabry disease, glycogen storage diseases), endomyocardial disease (endomyocardial fibrosis — common in tropical regions, Loeffler endocarditis from eosinophilic infiltration), and radiation-induced fibrosis. RCM must be differentiated from constrictive pericarditis (which is surgically treatable with pericardiectomy) — both cause diastolic heart failure with similar presentation. Key differentiating features on cardiac catheterization: RCM shows discordant ventricular pressure changes during respiration, while constrictive pericarditis shows concordant changes (ventricular interdependence).