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Hypertrophic cardiomyopathy (HCM) is a condition in which the heart muscle becomes thick. The thickening makes it harder for blood to leave the heart, forcing the heart to work harder to pump blood.

Hypertrophic cardiomyopathy is a major cause of death in young athletes who seem completely healthy but die during heavy exercise.

Causes, incidence, and risk factors

The occurrence rate of HCM is 1 in 500 of the general population and 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.

Younger people are likely to have a more severe form of hypertrophic cardiomyopathy. However, the condition is seen in people of all ages.

Learn more about athlete heart screenings

Symptoms

  • Chest pain
  • Dizziness
  • Fainting, especially during exercise
  • Heart failure (in some patients)
  • High blood pressure (hypertension)
  • Light-headedness , especially with or after activity or exercise
  • Sensation of feeling the heart beat (palpitations )
  • Shortness of breath

Other symptoms that may occur are:

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

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.

Signs and tests

Your health care provider will perform a physical exam and listen to the heart and lungs with a stethoscope. Listening with a stethoscope may reveal abnormal heart sounds or a murmur.

Tests used to diagnose heart muscle thickness, problems with blood flow, or leaky heart valves (mitral valve regurgitation ) may include:

  • 24-hour Holter monitor (heart monitor)
  • Cardiac catheterization
  • Chest x-ray
  • ECG
  • Echocardiography (the most common test) with Doppler ultrasound
  • MRI of the heart
  • Transesophageal echocardiogram (TEE)

Expectations (prognosis)

Some people with hypertrophic cardiomyopathy may not have symptoms and live a normal lifespan. Others may get worse gradually or rapidly. The condition may develop into a dilated cardiomyopathy in some patients.

People with hypertrophic cardiomyopathy are at higher risk for sudden death than the normal population. Sudden death can occur at a young age.

Hypertrophic cardiomyopathy is a well-known cause of sudden death in athletes. Almost half of deaths in hypertrophic cardiomyopathy happen during or just after the patient has done some type of physical activity.

If you have hypertrophic cardiomyopathy, always follow your doctor’s advice concerning exercise and medical appointments. Patients are sometimes advised to avoid strenuous exercise.

Contact your health provider if:

  • You have any symptoms of hypertrophic cardiomyopathy
  • You develop chest pain, palpitations, faintness, or other new or unexplained symptoms

Find a physician or call 1-877-THR-WELL

Prevention

If you are diagnosed with hypertrophic cardiomyopathy, your health care provider may recommend that your close blood relatives (family members) be screened for the condition.

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