Hypertrophic Cardiomyopathy


Hypertrophic cardiomyopathy (HCM) is a complex type of heart disease that affects the heart muscle. It causes thickening of the heart muscle (especially the ventricles, or lower heart chambers), left ventricular stiffness, mitral valve changes and cellular changes.

Sudden death can occur at a young age.

The first symptom of hypertrophic cardiomyopathy among many young patients is sudden collapse and possible death. This is caused by very abnormal heart rhythms (arrhythmias), or from the blockage of blood leaving the heart to the rest of the body.

Some people with hypertrophic cardiomyopathy may not have symptoms at all and live a normal lifespan. Patients with no symptoms may not even realize they have the condition until it is found during a routine medical exam.

It may get worse gradually or rapidly and this condition can develop into a dilated cardiomyopathy.


Human and Social Costs

  • Cardiomyopathy is a leading cause of heart failure and the most common reason for needing a heart transplant.
  • Hypertrophic cardiomyopathy affects an estimated 600,000 to 1.5 million Americans, or one in 500 people. It is more prevalent than multiple sclerosis, which affects one in 700 people.
  • People with hypertrophic cardiomyopathy are at higher risk for sudden death than the normal population.
  • Almost half of deaths in hypertrophic cardiomyopathy happen during or just after the patient has done some type of physical activity.  It is not uncommon for patients to be advised to avoid strenuous exercise.
  • Hypertrophic cardiomyopathy is a well-known, major cause of death in young athletes who seem completely healthy but die during heavy exercise.  However, certain normal changes in athletes' hearts can confuse the diagnosis.