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Hypertrophic Cardiomyopathy
Hypertrophic cardiomyopathy is a condition in which your heart muscle is thicker than normal. It can interfere with your heart's ability to pum...

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What is Hypertrophic Cardiomyopathy?

Hypertrophic cardiomyopathy (HCM) is a condition where your heart muscle, or myocardium, becomes thicker than normal. This interferes with your heart’s ability to pump blood.

In most cases, HCM doesn’t cause any symptoms. People with HCM are generally able to lead normal lives. However, some cases can become serious. This may happen either slowly or suddenly.

According to the Cleveland Clinic, HCM occurs in one in every 500 people in the United States (CC).

What Causes HCM?


HCM is typically an inherited condition. Defective genes cause the heart muscle to thicken. You have a 50 percent chance of inheriting one of these genes if one of your parents is affected by HCM. You have a 75 percent chance if both parents are affected.

Inheriting the gene doesn’t necessarily mean that you’ll have symptomatic disease. HCM follows a dominant pattern of inheritance. However, symptoms do not always develop in people with the defective gene.

Other Causes

Other possible causes of HCM include aging and high blood pressure. In some cases, the cause of HCM is never identified.

Recognizing the Symptoms of HCM

Many people with HCM don’t experience any symptoms. However, the following symptoms may occur during physical activity:

  • chest pain
  • shortness of breath
  • fainting
  • dizziness

Other symptoms that might occur, at any time, include:

  • fatigue
  • shortness of breath
  • heart palpitations, which are pounding or fluttering heartbeats
  • high blood pressure

Testing for and Diagnosing HCM

A number of different tests can be used to diagnose HCM.

Physical Exam

Your doctor will listen for a heart murmur or unusual heartbeats. Heart murmurs may occur if thickened heart muscle disrupts blood flow to the heart.


This is the most common diagnostic test for HCM. An echocardiogram creates images of your heart using sound waves. Your doctor will look for any unusual movements.


This test is used to measure the electrical activity in your heart. HCM can cause abnormal results.

Holter Monitor

This is a portable electrocardiogram that you can wear throughout the day. Your doctor will have you wear it for 24 to 48 hours. This allows your doctor to see how your heartbeat changes during different activities.

Cardiac MRI

This test uses a magnetic field to produce detailed images of your heart.

Cardiac Catheterization

This test is used to measure the blood flow pressure in your heart and look for blockages. To perform this test, your doctor places a catheter in one of the arteries near your groin. The catheter is carefully threaded up through your arteries to your heart. Once at your heart, dye is injected so that the doctor can take detailed X-ray images.

Potential Long-Term Complications of HCM

Many people with HCM will never have any serious health problems caused by it. However, HCM can cause severe complications in some people. The most common complications of HCM are listed below.

Sudden Cardiac Arrest

Sudden cardiac arrest occurs when the heart suddenly stops working. This condition is also called “sudden cardiac death.” This is typically caused by a rapid heart rhythm known as ventricular tachycardia. Without emergency treatment, sudden cardiac arrest can be fatal. HCM is the leading cause of sudden cardiac death in people who are under 30.

You might be at higher risk for sudden cardiac death if you have at least one of these conditions:

  • family history of sudden cardiac death
  • poor heart function
  • severe symptoms
  • history of irregular heart rhythms with a fast heart rate
  • fainting on several occasions (only applies if you’re young)
  • unusual blood pressure response to physical activity

Heart Failure

When your heart doesn’t pump the amount of blood that your body needs, you are said to be in heart failure.

Dilated Cardiomyopathy

This diagnosis means your heart muscle has become weak and enlarged. The enlargement makes your heart work less effectively.

Infective Endocarditis

When the inner lining of your heart or your heart valves become infected, it is known as infective endocarditis. This can happen when bacteria or fungi enter your blood stream and get into your heart. Infectious endocarditis can cause tissue scarring, holes, or growths in the heart valves. It can be fatal without treatment.

How Is HCM Treated?

Treatment for HCM focuses on relieving symptoms and preventing complications, especially sudden cardiac death. The methods used depend on your:

  • symptoms
  • age
  • activity level
  • heart function


Beta-blockers and calcium channel blockers relax your heart muscle. Relaxation helps it work better.

If you have an irregular heart rhythm, your doctor might prescribe antiarrhythmic medications, such as amiodarone.

You might need to take antibiotics before dental procedures or surgery to lower your risk of infective endocarditis.

Septal Myectomy

This procedure removes part of the thickened septum, the heart muscle wall between the two lower heart chambers, the ventricles, to help the blood flow through the heart better.

A septal myectomy would be used only if medications don’t reduce symptoms.

Septal Ablation

This procedure uses alcohol to destroy part of the thickened heart muscle. The alcohol is injected through a catheter placed in the artery that supplies the part of your heart that is being treated.

A septal ablation is often done in people who can’t have a septal myectomy.

Pacemaker Implantation

If there is irregular heart rate and rhythm, a tiny electronic device called a pacemaker can be placed under the skin on your chest. The pacemaker helps regulate your heart rate by sending electrical signals to your heart.

This procedure is less invasive than septal myectomies and ablations. It’s also usually less effective.

Implantable Cardioverter-Defibrillator (ICD)

This small device uses electric shocks to track your heartbeat and fix dangerous, abnormal heart rhythms. It is placed inside your chest.

ICD is often used in people who have a high risk of sudden cardiac death.

Lifestyle Changes

If you have HCM, your doctor may recommend lifestyle changes to reduce the risk of complications. These include:

  • eating a healthy diet
  • keeping your weight at a healthy level
  • doing low-intensity physical activities
  • limiting alcohol intake, as alcohol can cause abnormal heart rhythms

Coping and Getting Support

Having a disease like severe HCM can lead to emotional problems. Some people have trouble coping with the adjustments they have to make, such as restricting exercise and relying on medication for the rest of their lives.

If you’re having difficulty coping with HCM, your doctor might recommend seeing a therapist or joining a support group. You might also benefit from medications used to treat anxiety or depression.

Written by: Amanda Delgado
Edited by:
Medically Reviewed by:
Published: Aug 7, 2012
Published By: Healthline Networks, Inc.
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