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Cardiomyopathy: Overview

What is cardiomyopathy?

Cardiomyopathy is a problem with the heart muscle that can cause heart failure. There are 3 main types of cardiomyopathy:

  • Hypertrophic cardiomyopathy (HCM). The heart muscle cells get bigger. This makes the walls of the heart muscle thick. When the walls of the heart get too thick, the heart cannot pump well. Thick walls are usually very stiff, making it hard for the heart to fill with enough blood to pump. Some people with HCM develop a weak heart muscle over time. The weak heart muscle can slowly change to be dilated cardiomyopathy.
  • Restrictive cardiomyopathy. The heart muscle gets very stiff. This may be caused by deposits (like iron) that build up in the heart muscle or by scars that form on the inside of the heart. The stiffness makes it hard for the heart to fill with blood and pump properly. This is the least common kind of cardiomyopathy.

How does it occur?

The heart muscle may be weakened by many things.

  • Coronary artery disease (CAD) causes poor blood supply to the heart and may hurt the heart muscle, making it weak. This is the most common cause of dilated cardiomyopathy.
  • Cocaine or heavy alcohol use can weaken the heart muscle.
  • Some medicines used to treat cancer are deadly to heart muscle cells and can weaken the heart.
  • Sometimes viruses can weaken the heart muscle.

Often what causes the heart to enlarge and weaken is not known. When the cause is not known, it is called idiopathic dilated cardiomyopathy.

Hypertrophic cardiomyopathy may be caused by high blood pressure. High blood pressure makes the heart pump harder. The walls of the heart enlarge just like the muscles of a weight lifter get bigger. When high blood pressure goes untreated for many years, the heart muscle will get thicker and you may develop hypertrophic cardiomyopathy. HCM often runs in families. It may be caused by abnormal proteins that control heart muscle growth. The heart tries to make up for this by enlarging, becoming thick and deformed.

Many diseases, including some cancers and infections, can cause restrictive cardiomyopathy. These diseases cause scar tissue to build up on the inner surface of the heart or within the walls of the heart. This scarring keeps the heart from filling with blood fully, so it cannot pump properly.

What are the symptoms?

Cardiomyopathy may not cause symptoms. If it does, the symptoms may include:

  • chest pain
  • shortness of breath with physical activity
  • waking up short of breath
  • swelling of the legs or ankles
  • dizziness
  • fainting.

How is it diagnosed?


  • chest X-rays
  • coronary angiography, which is an X-ray test that helps find blockages in the coronary arteries.


Because the disease may run in families, your provider may suggest testing other members of your family.

How is it treated?


Medicines such as beta blockers or calcium channel blockers may be used to relax the heart muscle. Your healthcare provider may prescribe a drug called a vasodilator. It makes the blood vessels open up. The increased size of the blood vessels lets more blood to flow through them. This lowers blood pressure slightly so the heart does not have to work as hard. ACE inhibitors are another type of medicine that can relax blood vessels and lower blood pressure. This helps the heart to pump more blood out to the body.

Your healthcare provider may prescribe a drug called a diuretic. It helps your body get rid of the buildup of fluid that can happen when the heart does not pump effectively.

Your healthcare provider may also prescribe a blood thinner (anticoagulant). Blood thinners help to keep the blood from clotting and prevent artery blockages and strokes.

Procedures that may be used to treat cardiomyopathy include:

  • myectomy (muscle removal), which in some cases can be done with a heart catheter so that surgery is not required
  • implanting an artificial pacemaker or a cardioverter-defibrillator (ICD) to treat abnormal heart rhythms.

How long will the effects last?

The effects of cardiomyopathy depend on what has caused it. If it is caused by coronary artery disease, you are likely to have a weakened heart muscle for the rest of your life, but medicine may help the heart muscle function better. Other types of cardiomyopathy may improve over weeks to months, depending on the cause.

How can I take care of myself?

  • Take your medicines regularly, carefully following your healthcare provider instructions.
  • Weigh yourself regularly and let you provider know if you suddenly gain weight.
  • Call your healthcare provider if you have changes such as shortness of breath, lightheadedness, or chest pain.

How can I help prevent cardiomyopathy?

  • Do not smoke.
  • Follow your healthcare provider's recommendations. If you have high cholesterol or hypertension, take the medicines that have been prescribed for you to treat these conditions.


HIA File card3611.htm Release 13/2010

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