Possible Causes of Dilated Cardiomyopathy
Coronary artery disease. The most common cause of cardiomyopathy in developed nations is coronary artery disease. Heart attacks occur when a coronary artery becomes obstructed, leading to the death of heart muscle cells. While the initial heart muscle damage is located only in the region of muscle supplied by the blocked artery, within a few months the entire left ventricle dilates (or "remodels") to compensate for the damage. With a small heart attack, the amount of ventricular dilation is minimal. But with a large heart attack or a series of smaller heart attacks, dilated cardiomyopathy becomes extensive, and heart failure is the eventual result.
Myocarditis. Inflammation of the heart muscle is called myocarditis. Myocarditis is most often caused by viral infections, but can also be caused by bacterial infections and by non-infectious causes such as lupus and other inflammatory diseases.
Alcohol. Alcohol is another cause of cardiomyopathy. In some patients (probably determined by genetic predisposition), alcohol acts as a powerful toxin to heart muscle, directly damaging cardiac cells. Alcoholic cardiomyopathy can be seen after as few of five years of excessive alcohol intake.
Valvular heart disease. Valvular heart disease, especially aortic regurgitation and mitral regurgitation, cause dilated cardiomyopathy. Indeed, the gradual enlargement of the cardiac chambers is an important sign that the time may be right for valve replacement or repair.
High blood pressure. While hypertension tends to produce hypertrophic cardiomyopathy or diastolic dysfunction, eventually it can also result in a 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. Cardiomyopathy sometimes develops in women within a month of delivering a baby. This so-called peripartum cardiomyopathy is the result of a myocarditis that occurs for unknown reasons, associated with childbirth. While many of the affected women recover completely, others develop a rapid and severe dilated cardiomyopathy.
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." Cardiac "overwork" is another cause of dilated cardiomyopathy. Any condition that causes the heart muscle to work at high loads for 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, chronic hyperthyroidism, and the overwork produced by leaky (regurgitant) heart valves.
Broken heart syndrome. There is an unusual form of generally reversible dilated cardiomyopathy called stress cardiomyopathy, or broken heart syndrome. Stress cardiomyopathy is seen in otherwise healthy patients (usually women), who are exposed to sudden, severe emotional trauma. Symptoms include severe shortness of breath and chest pain - strongly suggesting a heart attack - and patients become critically ill with heart failure. But with appropriate care they survive and the cardiomyopathy disappears in short order. The cause of stress cardiomyopathy is unknown. This syndrome, fortunately, is rare.
Idiopathic. In many cases, specific causes of dilated cardiomyopathy cannot be identified. In these cases, the dilated cardiomyopathy is said to be "idiopathic."
More on Dilated Cardiomyopathy
Symptoms and Diagnosis of Dilated CardiomyopathyTreatment of Dilated Cardiomyopathy
Additional Links Related to Heart Failure
Sources:
Massie, BM "Heart Failure" in: Goldman L and Ausiello D (Eds). Cecil Textbook of Medicine, WB Saunders, 2003
