Hypertrophic cardiomyopathy (HCM) is a disease in which the heart muscle becomes thickened, also called hypertrophied. The thickened heart muscle can make it harder for the heart to pump blood.
Many people with hypertrophic cardiomyopathy don't realize they have it. That's because they have few, if any, symptoms. But in a small number of people with HCM, the thickened heart muscle can cause serious symptoms. These include shortness of breath and chest pain. Some people with HCM have changes in the heart's electrical system. These changes can result in life-threatening irregular heartbeats or sudden death.