Dilated cardiomyopathy occurs most often in middle-age people and more often in men than women. However, the disease has been diagnosed in people of all ages, including children.

In most cases, the disease is idiopathic--a specific cause for the damage is never identified.

But some factors have been linked to the disease's occurrence. For instance, alcohol has a direct suppressant effect on the heart, and chronic, excessive consumption of alcohol may cause dilated cardiomyopathy. Also, dilated cardiomyopathy occasionally occurs as a complication of pregnancy and childbirth. Other factors are: a variety of infections, mostly viral, which lead to an inflammation of the heart muscle (myocarditis); toxins (such as cobalt); and, rarely, heredity.

Some drugs, used to treat a different medical condition, also can damage the heart and produce the condition. Such drugs include doxorubicin and daunorubicin, both used to treat cancer.

This condition is commonly called "heart failure," and it is the hallmark of dilated cardiomyopathy. Typical signs and symptoms of heart failure include: fatigue; weakness; shortness of breath, sometimes severe and accompanied by a cough, particularly with exertion or when lying down; and swelling of the legs and feet, resulting from fluid accumulation that may also affect the lungs (congestion) and other parts of the body and that produces abnormal weight gain. (The cough and congestion mimic, and so can be misdiagnosed as, pneumonia or acute bronchitis.)

Because of the congestion, some physicians use the older term "congestive cardiomyopathy" to refer to dilated cardiomyopathy. In advanced stages of the disease, the congestion may cause pain in the chest or abdomen.

However, the disease also can remain fairly stable for years, especially with treatment and regular evaluation by a physician.

Unfortunately, by the time it is diagnosed, the disease often has reached an advanced stage, and heart failure has occurred. Consequently, about 50 percent of patients with dilated cardiomyopathy live 5 years once heart failure is diagnosed; about 25 percent live 10 years after such a diagnosis.

Typically, patients die from a continued decline in heart muscle strength, but some die suddenly of irregular heartbeats.

For patients with advanced disease, heart transplantation greatly improves survival: 75 percent of patients live 5 years after a transplantation. However, the scarcity of donor hearts limits its availability to about 2,000 Americans a year. People who qualify for heart transplantation often have to wait months, or even years, for a suitable donor heart. Some patients with dilated cardiomyopathy die awaiting a transplant but, according to recent studies, others improve enough from aggressive medical treatment to be taken off the waiting list.

The goal of treatment is to relieve any complicating factor, if known, control the symptoms, and stop the progression. However, no cure now exists.

Promising clues came from a team of NHLBI investigators that discovered some of the genes responsible for hypertrophic cardiomyopathy. Their work represents an important first step in understanding how the disease is transmitted and how it progresses.

Researchers also are trying to determine the best use of currently available treatments, especially drug therapies. Drugs useful for other conditions may help treat cardiomyopathy. For example, drugs effective in treating high blood pressure also help manage heart failure and irregular heartbeats.

Additionally, much work has been--and continues to be--done on identifying factors that increase or decrease a person's risk of death in cardiomyopathy. Knowing which patients are at the greatest risk is very important in determining the best approach to the evaluation and treatment of their condition.

The development of improved treatments for cardiomyopathy, however, awaits still more research and a better understanding of the disease process.