Dilated cardiomyopathy (DCM) is a condition in which the heart's ability to pump blood is decreased because the heart's main pumping chamber, the left ventricle, is enlarged and weakened; this causes a decreased ejection fraction (the amount of blood pumped out with each heart beat). In some cases, it prevents the heart from relaxing and filling with blood as it should. Over time, it can affect the other heart chambers as well.

What Are the Symptoms of DCM?

Many people with DCM have no symptoms or only minor symptoms, and live a normal life. Other people develop symptoms, which may progress and worsen as heart function worsens.

Symptoms of DCM can occur at any age and may include:

Heart failure symptoms (shortness of breath and fatigue).
Swelling of the lower extremities.
Fatigue (feeling overly tired).
Weight gain.
Fainting (caused by conditions such as irregular heart rhythms, abnormal responses of the blood vessels during exercise, or no cause may be found).
Palpitations (fluttering in the chest due to abnormal heart rhythms).
Dizziness or lightheadedness.
Blood clots due to blood flowing more slowly through the body. If a blood clot breaks off, it can be carried to the lungs (pulmonary emboli), kidney (renal emboli), brain (cerebral emboli or stroke), or limbs (peripheral emboli).
Chest pain or pressure (occurs usually with exercise or physical activity, but can also occur with rest or after meals).

What Causes DCM?

DCM can be inherited (familial DCM), but it is primarily caused by a variety of other factors, including:

Severe coronary artery disease
Alcoholism
Thyroid disease
Diabetes
Viral infections of the heart
Heart valve abnormalities
Drugs that are toxic (or cause damage) to the heart

It can also occur in women after childbirth (postpartum cardiomyopathy).

Most cases of DCM are idiopathic (an exact cause is not known). When that's the case, the condition is called idiopathic dilated cardiomyopathy or dilated nonischemic cardiomyopathy.

How Is DCM Diagnosed?

DCM is diagnosed based on medical history (your symptoms and family history), physical exam, and tests: such as blood tests, electrocardiogram, chest X-ray, echocardiogram, exercise stress test, cardiac catheterization, CT scan, and MRI.

Another test rarely done to determine the cause of a cardiomyopathy is a myocardial biopsy, or heart biopsy, where a tissue sample is taken from the heart and examined under a microsope to determine the cause of the symptoms.

Relatives of those with familial DCM should be screened for DCM. Testing would be the same as mentioned above (medical history, physical exam, ECG, echocardiogram, etc.). Genetic testing may also be available to identify abnormal genes.

What Is the Treatment for DCM?

Treatment of DCM is aimed at correcting the cause of the condition wherever possible. Another major goal is to decrease the heart size and decrease the substances (hormones) in the bloodstream that enlarge the heart and ultimately lead to worsened symptoms. Patients usually take several medications to treat the heart failure. Doctors also recommend a variety of lifestyle changes.

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