Common Causes of Dilated Cardiomyopathy

Dilated cardiomyopathy is a condition in which one or both of the heart’s ventricles becomes weakened and dilated. It often leads to heart failure and cardiac arrhythmias—especially atrial fibrillation—and can lead to sudden death. Dilated cardiomyopathy is the most common of the three types of cardiomyopathy (heart muscle disease), the other two being hypertrophic cardiomyopathy and restrictive cardiomyopathy.​

Doctor conducting medical exam
PhotoAlto / Eric Audras / Getty Images

What Is Dilation and Why Is It Important?

Virtually any medical condition that can produce a weakening of the heart muscle can lead to dilated cardiomyopathy. When the cardiac muscle weakens, it is unable to contract fully. The heart attempts to compensate for this weakening by a process called remodeling, which virtually always leads to the dilation of the cardiac chambers.

The dilation stretches the heart muscle, which helps—for a time, at least—to preserve some of the force of muscular contraction. In addition, a dilated ventricle is able to hold more blood. As a result of the dilation, even if a weakened ventricle is able to eject, say, only 30% of the blood it is holding (as compared to the normal 55%), the total volume of blood ejected with each heartbeat may be maintained—to a point. (The percentage of blood that is ejected from the left ventricle with each heartbeat is called the left ventricular ejection fraction, or LVEF. Measuring the LVEF turns out to be an important way to assess overall cardiac health.)

The bottom line is that dilation of the cardiac chambers is a compensatory mechanism that provides some short-term relief if the heart muscle is weakened. Unfortunately, in the long term, the dilation itself tends to further weaken the heart muscle. Eventually, overt heart failure often develops.

If you have dilated cardiomyopathy, it will be important for you and your healthcare provider to work together to identify the underlying cause, since aggressively treating the underlying cause is often critical to preventing the progression to heart failure.


Almost any cardiac disease that can damage the cardiac muscle can lead to dilated cardiomyopathy. The most common causes are:

  • Coronary artery disease (CAD): CAD is the most common cause of dilated cardiomyopathy. CAD most often produces dilated cardiomyopathy by causing myocardial infarctions (heart attacks), which damage the heart muscle.
  • Infections: Several infectious diseases can attack and weaken the heart muscle. These include numerous viral infections, Lyme disease, HIV infection, and Chagas disease.
  • Valvular heart disease: Valvular heart disease, especially aortic regurgitation and mitral regurgitation, often produce dilated cardiomyopathy.
  • High blood pressure: While hypertension tends to produce hypertrophic cardiomyopathy or diastolic dysfunction, it can also eventually result in dilated cardiomyopathy.
  • Alcohol: In some genetically predisposed individuals, alcohol acts as a powerful toxin to the heart muscle and leads to dilated cardiomyopathy.
  • Cocaine: Cocaine usage has also been associated with dilated cardiomyopathy.
  • Thyroid disease: Thyroid disease—either hyperthyroidism (thyroid gland too active) or hypothyroidism (thyroid gland not active enough)—can lead to heart failure. Hyperthyroidism is more likely to cause dilated cardiomyopathy, whereas hypothyroidism is more likely to cause diastolic heart failure.
  • Nutritional: Nutritional abnormalities—especially a deficiency in vitamin B1—can cause cardiomyopathy. This form of cardiomyopathy is mostly seen in developing nations, and in alcoholics.
  • Postpartum: Postpartum cardiomyopathy is a form of cardiomyopathy associated with childbirth that occurs for unknown reasons.
  • Genetic: There are also genetic forms of dilated cardiomyopathy. This is why some families are clearly affected by an extremely high incidence of dilated cardiomyopathy.
  • Autoimmune diseases: Lupus and celiac disease are autoimmune processes that can lead to dilated cardiomyopathy.
  • Cardiac overwork: Any condition that causes the heart muscle to work very hard for very prolonged periods of time (weeks or months) can eventually cause cardiac dilation and weakening of the heart muscle. Such conditions include prolonged severe anemia, abnormal sustained tachycardias (rapid heart rates), chronic hyperthyroidism, and the overwork produced by leaky (regurgitant) heart valves.
  • Stress cardiomyopathy: Stress cardiomyopathy, also known as “broken heart syndrome,” is a form of acute heart failure associated with severe stress.
  • Miscellaneous conditions: Several other conditions can cause dilated cardiomyopathy, including sarcoidosis, end-stage kidney disease, and obstructive sleep apnea.
  • Idiopathic: Sometimes, specific causes of dilated cardiomyopathy cannot be identified. In these cases, the dilated cardiomyopathy is said to be idiopathic.

A Word From Verywell

Adequately treating your dilated cardiomyopathy requires that your healthcare provider make every attempt to identify the underlying cause, then treat that underlying cause to the fullest extent possible. If you or a loved one has been told you have dilated cardiomyopathy, talk to your healthcare provider about the cause of your condition and what treatment options are available.

Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  • Biagini E, Coccolo F, Ferlito M, et al. Dilated-hypokinetic Evolution of Hypertrophic Cardiomyopathy: Prevalence, iIcidence, Risk Factors, and Prognostic iIplications in Pediatric and Adult Patients. J Am Coll Cardiol 2005; 46:1543.
  • Luk A, Ahn E, Soor GS, Butany J. Dilated Cardiomyopathy: a Review. J Clin Pathol 2009; 62:219.

By Richard N. Fogoros, MD
Richard N. Fogoros, MD, is a retired professor of medicine and board-certified in internal medicine, clinical cardiology, and clinical electrophysiology.