Cardiomyopathy is a condition of abnormal heart muscle without apparent cause. There are four types of cardiomyopathy: Hypertrophic (HCM), Dilated (DCM), Restrictive (RCM) and Arrhythmogenic Right Ventricular (ARVC). The main feature of Hypertrophic Cardiomyopathy is an excessive thickening of the heart muscle (hypertrophy literally means to thicken). Heart muscle may thicken in normal individuals as a result of high blood pressure or prolonged athletic training. In Hypertrophic Cardiomyopathy, however, the muscle thickening occurs without an obvious cause. In addition, microscopic examination of the heart muscle in Hypertrophic Cardiomyopathy shows an abnormality called myocardial disarray.