Dilated Cardiomyopathy (DCM)

What is dilated cardiomyopathy?

Dilated cardiomyopathy (DCM) is a condition that affects the muscle of the heart, usually the left ventricle, and causes the heart to become enlarged. When the heart becomes enlarged the muscle becomes weak and floppy which makes it unable to pump blood efficiently. This decreased heart function can also lead to fluid accumulation that affects the lungs as well as other tissues and organs in the body.

Who is affected by DCM?

DCM affects about 1 in 2500 individuals, although the true incidence is thought to be higher because many people do not have symptoms until severe heart failure develops.

Genetics and DCM

The causes of DCM can be attributed to several known causes, including viral infection, autoimmune disease, excessive alcohol exposure, and exposure to toxic chemicals. However, about 25-35% of cases of DCM are believed to be caused by a genetic mutation (change). These mutations occur in genes responsible for making proteins that function in the heart muscle. They can also be passed down (inherited) in families. The risk to family members of inheriting a mutation associated with DCM is dependent on the type of inheritance pattern that is seen in an individual family, but this risk can be as high as 50%. Because of this risk, it is important that family members (siblings, children, and parents) of affected individuals be evaluated by a physician.

So far, 17 genes that cause DCM have been identified and several more are currently being investigated.

What are the symptoms of DCM?

Symptoms and age of onset will vary between individuals. On average patients will present with symptoms between 20 and 50 years of age, however, older or younger individuals have been diagnosed as well. Symptoms associated with DCM are often the same as those seen with heart failure and include:

- Shortness of breath

- Swelling or accumulation of fluid in ankles, belly, or other areas

- Fatigue

- Heart palpitations (often described as a feeling of fluttering)

- Fainting of loss of consciousness (syncope)

- Chest pains

How is DCM diagnosed?

A careful assessment of a family history, a thorough physical exam, and several heart tests can be used to make the diagnosis of DCM. There are also certain diagnostic criteria that must be met, based on the results of these tests.

Some of the tests used to diagnose DCM include:

- Electrocardiogram (ECG): This test is performed by placing electrodes on the body and measuring the electrical signal through the heart as it beats. By reviewing the pattern of this electrical signal, the doctor can determine if the heart is beating normally.

- Echocardiogram (ECHO): This test is an ultrasound of the heart. It is performed by placing a wand on the chest that transmits sound waves; these waves create a picture of the heart. This picture can be used to determine whether or not the heart is enlarged.

- Blood tests: Some blood tests can be used to tell how the heart is functioning or if there is muscle damage. These tests alone cannot be used to diagnose cardiomyopathy, but they may be used in conjunction with the tests listed above.

Additional testing may be necessary if the results of the above tests warrant closer investigation. Additional testing options include:

- Chest X-ray: May be used to see enlargement of the heart or fluid in the lungs.

- Magnetic Resonance Imagining (MRI): Provides a more detailed picture of the heart than an ECHO.

- Holter monitor: Measures heart rhythm over a 24-hour period.

Is there any treatment for DCM?

Treatments focus on using medications (ACE inhibitors, beta-blockers, digoxin, diuretics, anticoagulants, etc) to relieve symptoms and to prevent complications as well as to slow disease progression. In addition to drug therapies other supportive measures including weight control, limited sodium intake, moderation of alcohol, and approved exercise are encouraged. For some individuals with symptoms of arrhythmia, a pacemaker or implantable cardioverter defibrillator (ICD) can be inserted to help maintain a normal rhythm of the heart. A heart transplant is optional if symptoms are severe and no other form of treatment helps to lessen the symptoms. Individuals with DCM should establish a personalized management plan with his or her cardiologist that involves regular checkups and maintenance. Currently, there is no known cure for DCM.

Genetic testing options

Of the genes that are currently known to be associated with DCM, very few are available for clinical testing at this time. For more information regarding current clinical testing options, contact your local doctor to find out where genetic counseling services are available in your area.

Genetic testing is currently available as part of a research protocol through the University of Colorado Denver Cardiovascular Institute. For more information, please go to our Familial Cardiomyopathy Study section.

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