Often, the cause of the cardiomyopathy is unknown. In some people, however, doctors are able to identify some contributing factors. Possible causes of cardiomyopathy include:

  • Long-term high blood pressure
  • Heart valve problems
  • Heart tissue damage from a previous heart attack
  • Chronic rapid heart rate
  • Metabolic disorders, such as obesity, thyroid disease or diabetes
  • Nutritional deficiencies of essential vitamins or minerals, such as thiamin (vitamin B-1)
  • Pregnancy
  • Drinking too much alcohol over many years
  • Use of cocaine, amphetamines or anabolic steroids
  • Use of some chemotherapy drugs to treat cancer
  • Certain viral infections, which may injure the heart and trigger cardiomyopathy
  • Iron buildup in your heart muscle (hemochromatosis)
  • Genetic conditions

The three types of cardiomyopathy are:

  • Dilated cardiomyopathy. This is the most common type of cardiomyopathy. In this disorder, the pumping ability of your heart's main pumping chamber — the left ventricle — becomes less forceful. The left ventricle becomes enlarged (dilated) and can't effectively pump blood out of the heart. Although this type can affect people of all ages, it occurs most often in middle-aged people and is more likely to affect men. Some people with dilated cardiomyopathy have a family history of the condition. In others, dilated cardiomyopathy may occur as a result of infection, chemotherapy or alcohol use. The cause may also be unknown (idiopathic).
  • Hypertrophic cardiomyopathy. This type involves abnormal growth or thickening of your heart muscle, particularly affecting the muscle of your heart's main pumping chamber. As thickening occurs, the heart tends to stiffen and the size of the pumping chamber may shrink, interfering with your heart's ability to deliver blood to your body. Hypertrophic cardiomyopathy can develop at any age, but the condition tends to be more severe if it becomes apparent during childhood. Most affected people have a family history of the disease, and some genetic mutations have been linked to hypertrophic cardiomyopathy.
  • Restrictive cardiomyopathy. The heart muscle in people with restrictive cardiomyopathy becomes rigid and less elastic, meaning the heart can't properly expand and fill with blood between heartbeats. While restrictive cardiomyopathy can occur at any age, it most often tends to affect older people. It's the least common type of cardiomyopathy and can occur for no known reason (idiopathic). The condition may also be caused by diseases elsewhere in the body that affect the heart, such as a disorder that causes the buildup of abnormal proteins (amyloidosis) or a disorder that causes abnormal blood cells to damage the heart (eosinophilic heart disease).
Jan. 24, 2014

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