Hypertrophic cardiomyopathy
（重定向自Idiopathic hypertrophic subaortic stenosis）
Hypertrophic cardiomyopathy (HCM) is a primary disease of the myocardium (the muscle of the heart) in which a portion of the myocardium is hypertrophied (thickened) without any obvious cause, creating functional impairment of the cardiac muscle. It is a leading cause of sudden cardiac death in young athletes. The occurrence of hypertrophic cardiomyopathy is a significant cause of sudden unexpected cardiac death in any age group and as a cause of disabling cardiac symptoms. Younger people are likely to have a more severe form of hypertrophic cardiomyopathy.