Dilated cardiomyopathy occurs when your heart's main pumping chamber (the left ventricle) doesn't pump as efficiently as a healthy heart. The muscles of the left ventricle stretch and become thinner (dilate). Dilating causes the heart muscle to weaken, and over time, the condition can cause heart failure.

Often, the cause of dilated cardiomyopathy can't be determined. Such cases are called idiopathic dilated cardiomyopathy.

There are numerous conditions that can cause the left ventricle to dilate and weaken. One example is damage that occurs during a heart attack. Strictly speaking, this isn't cardiomyopathy. Cardiomyopathy is a primary problem affecting the heart muscle. Damage that occurs after a problem such as a heart attack is considered a secondary cause. Still, many people use the term cardiomyopathy to describe secondary causes of heart muscle weakness.

Some known causes of dilated cardiomyopathy are:

  • Genetics. A number of genes are linked to dilated cardiomyopathy.
  • Birth defects. Certain heart defects that are present at birth (congenital) may cause dilated cardiomyopathy.
  • Infections. Many different types of infections, including those caused by bacteria, viruses, fungi and parasites, can cause dilated cardiomyopathy.
  • Drug and alcohol abuse. Dilated cardiomyopathy can be caused by long-term use of alcohol or illegal drugs, such as cocaine.
  • Certain cancer medications. Some drugs that are used in chemotherapy may cause dilated cardiomyopathy.
  • Exposure to toxins. This condition can also be caused by exposure to some metals and toxic compounds, such as lead, mercury and cobalt.
Sep. 16, 2011