Hypertrophic Cardiomyopathy Health Channel

Definition

Hypertrophic cardiomyopathy (HCM) is a form of cardiomyopathy, a condition in which the heart muscle to become thick. The thickening makes it harder for the heart to work.

Alternative Names

Cardiomyopathy - hypertrophic (HCM); IHSS; Idiopathic hypertrophic subaortic stenosis; Asymmetric septal hypertrophy; ASH; HOCM; Hypertrophic obstructive cardiomyopathy

Causes, incidence, and risk factors

Hypertrophic cardiomyopathy is often asymmetrical, meaning one part of the heart is thicker than the other parts. The condition is usually passed down through families (inherited). It is believed to be a result of several problems (defects) with the genes that control heart muscle growth.

Because hypertrophic cardiomyopathy causes the size of one of the heart chambers (ventricular chamber) to shrink, the heart must work harder to pump blood. The thickening of the heart muscle may complete block the normal flow of blood out of the heart. It may also make it harder for the heart valves to work. Heart valves help control the direction of blood flow.

Younger people are likely to have a more severe form of hypertrophic cardiomyopathy. However, the condition is seen in people of all ages. In people over age 60, hypertrophic cardiomyopathy is often associated with mild hypertension (high blood pressure).

Symptoms

• Chest pain
• Fainting, especially during exercise
• Light-headedness, especially after activity or exercise
• Dizziness
• Sensation of feeling heart beat (palpitations)
• Shortness of breath

Additional symptoms that may occur are:

• Fatigue, reduced activity tolerance
• Shortness of breath when lying down

Some patients have no symptoms, and may not even realize they have the condition until it is found during a routine medical exam.

Unfortunately, the first symptom of hypertrophic cardiomyopathy among many young patients is sudden death, caused by severely abnormal heart rhythms (arrhythmias). Hypertrophic cardiomyopathy is a major cause of death in young athletes who seem completely healthy but die during heavy exercise.