Hypertrophic cardiomyopathy (HCM) is a disease in which the heart muscle (myocardium) becomes abnormally thick (hypertrophied). The thickened heart muscle can make it harder for the heart to pump blood.
Hypertrophic cardiomyopathy often goes undiagnosed because many people with the disease have few, if any, symptoms. In a small number of people with HCM, the thickened heart muscle can cause shortness of breath and problems in the heart's electrical system, resulting in life-threatening abnormal heart rhythms (arrhythmias).
Fortunately, people with hypertrophic cardiomyopathy often lead normal lives with no significant problems.