Because it can be caused by so many kinds of medical conditions, dilated cardiomyopathy is the most common form of cardiomyopathy (heart muscle disease) and heart failure. Dilated cardiomyopathy develops because some diseases damage and weaken the heart muscle. In partial compensation for this weakness, the cardiac chambers dilate, or enlarge. The body's attempts to compensate for the heart muscle weakness, unfortunately, often fall short, and heart failure eventually develops.
If you have dilated cardiomyopathy, it will be important for you and your doctor to work together to identify the underlying cause, since this is often a critical aspect of treating dilated cardiomyopathy and heart failure.
What Causes Dilated Cardiomyopathy?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.
- Myocarditis. Myocarditis is inflammation of the heart muscle, which can lead to scarring and fibrosis of the heart muscle. It is usually caused by infections, immune diseases, or toxins.
- 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, eventually it can also result in a dilated cardiomyopathy.
- Alcohol. In some genetically-predisposed individuals, alcohol acts as a powerful toxin to the heart muscle, and leads to 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 a 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 the result of a myocarditis that occurs for unknown reasons, associated with childbirth.
- 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.
- 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.
- Broken heart syndrome. This is a form of acute heart failure associated with severe stress, most often seen in women.
- Idiopathic. In many cases, specific causes of dilated cardiomyopathy cannot be identified. In these cases, the dilated cardiomyopathy is said to be "idiopathic."
Treating your dilated cardiomyopathy adequately requires that your doctor make every attempt to identify the underlying cause, and then treat that underlying cause to the fullest extent possible. If you or a loved one has been told you have dilated cardiomyopathy, make sure you talk to your doctor about the cause of your condition, and what might be done about it.
Luk A, Ahn E, Soor GS, Butany J. Dilated cardiomyopathy: a review. J Clin Pathol 2009; 62:219.