Although there are many conditions that may result in dilated cardiomyopathy, up to half of all dilated cardiomyopathy cases are thought to be hereditary, possibly resulting from a gene mutation passed from parent to child.

Laboratory studies have revealed the presence and role of certain genes involved in the growth of heart muscle. A faulty gene, for example, may not be able to limit heart muscle growth, thereby setting in motion the process of dilated cardiomyopathy and other conditions that can enlarge the heart.

Aside from genetic factors, there are several other conditions and factors that may result in dilated cardiomyopathy, including:

• Coronary artery disease (CAD). The coronary arteries supply the heart with the blood necessary for it to function. CAD is a chronic disease in which blood flow is obstructed through the coronary arteries. As a result, the heart is unable to work as effectively as it should. This can lead to dilated cardiomyopathy.
  
  
• High blood pressure. Poorly controlled or untreated high blood pressure can put unnecessary strain on the heart, leading to dilated cardiomyopathy.
  
  
• Excessive alcohol consumption. Alcohol damages the heart muscle over time. The Texas Heart Institute estimates that 30 percent of dilated cardiomyopathy cases are related to heavy drinking. This high proportion of cases may also be linked to the fact that heavy drinkers frequently neglect other aspects of their health, particularly nutrition, which is another risk factor for dilated cardiomyopathy.
  
  
• Other toxic substances. Aside from alcohol, there are several other substances that are toxic to the heart and may lead to dilated cardiomyopathy. These may include illegal drugs, such as cocaine or methamphetamine, or certain powerful medications used to treat cancer.
  
  
• Viral infections. Although rare, there are several viruses that have been linked to cardiomyopathy. Additionally, viral infections may cause myocarditis, inflammation of the heart muscle which may contribute to the risk of developing dilated cardiomyopathy.
  
  
• AIDS. Studies have shown that people with AIDS have a significant risk of developing dilated cardiomyopathy.
  
  
• Barth syndrome. This is a rare and relatively unknown genetically linked cardiac disease, that has been known to cause dilated cardiomyopathy. It usually affects male children in their first year of life.