What Is Dilated Cardiomyopathy?

Dilated cardiomyopathy (DCM) is the most common type of nonischemic cardiomyopathy. In dilated cardiomyopathy, the heart's ability to pump blood is decreased because the heart's main pumping chamber, the left ventricle, is enlarged, dilated and weak. At first, the chambers of the heart respond by stretching to hold more blood to pump through the body. This helps to strengthen the heart's contraction and keep the blood moving for a short while. With time, the heart muscle walls weaken and are not able to pump as strongly. The kidneys often respond by retaining fluid (water) and sodium. If fluid builds up in the legs, ankles, feet, lungs or other organs, the body becomes congested, and congestive heart failure is the term used to describe this condition.

What are the symptoms of DCM?

Many people with dilated cardiomyopathy have no symptoms or only minor symptoms. Other people develop symptoms, which may progress as heart function worsens.Symptoms of dilated cardiomyopathy can occur at any age and may include:

  • Shortness of breath.
  • Swelling of the legs and feet.
  • Fatigue (feeling overly tired), inability to exercise, or carry out activities as usual.
  • Weight gain, cough and congestion related to fluid retention.
  • Palpitations or fluttering in the chest due to abnormal heart rhythms (arrhythmia).
  • Dizziness or lightheadedness.
  • Fainting (caused by irregular heart rhythms, abnormal responses of the blood vessels during exercise, without apparent cause).
  • 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).
  • Learn more about heart failure symptoms.

What causes DCM?

  • Most cases of dilated cardiomyopathy are idiopathic (an exact cause is not known)
  • Sometimes a viral illness may be responsible
  • Occasionally it may be inherited (familial cardiomyopathy)
  • Heart valve disease (valvular cardiomyopathy)
  • Alcoholism (heavy drinking, alcoholic cardiomyopathy)
  • Drug abuse or taking d rugs that are toxic to the heart
  • Thyroid disease
  • Diabetes
  • Women after childbirth (peripartum cardiomyopathy).

When there is no known cause, the condition is called idiopathic dilated cardiomyopathy. About 1/3 of patients with idiopathic DCM have a family history, called familial dilated cardiomyopathy (ref). Familial DCM is a genetic condition. In rare autosomal dominant inheritance patterns (at least two family member have idiopathic DCM), first degree relatives (parents, siblings, children) have a 50 percent chance of inheriting the condition, and may benefit from risk screening or follow-up by a physician.

Last reviewed by a Cleveland Clinic medical professional on 04/29/2019.

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