What is cardiomyopathy?

In simple terms, cardiomyopathy refers to abnormal heart muscle. Some cases are mild and require no treatment. But in other cases, the condition causes severe symptoms (such as breathing difficulty and leg swelling) and leads to serious complications. Cardiomyopathy is one of many possible causes of heart failure, which happens when the heart is unable to pump well enough to meet the body's need for oxygen-carrying blood.

One of the most common forms, hypertrophic cardiomyopathy, is an abnormal thickening of the heart wall. The heart cannot fill completely, leaving less blood to pump out to the body. Although the condition can go unnoticed, it may cause a heart murmur that a doctor can detect with a stethoscope. The damaged heart cells may also disrupt the heart's electrical signals, leading to heart rhythm problems such as palpitations. In extreme cases, people with hypertrophic cardiomyopathy experience sudden cardiac arrest during vigorous physical activity; in fact, it's the most common cause of sudden death in athletes.

Hypertrophic cardiomyopathy is almost always caused by mutations in one of several genes that are passed down from one parent. People with a family history of the disease usually need routine heart ultrasounds to check for thickening of the heart muscle. The prognosis for this type of cardiomyopathy varies widely, but many people need medications and careful supervision throughout their lives.

The other main form, dilated cardiomyopathy, leads to distinctly different heart changes. The damaged heart muscle (usually the lower left chamber of the heart, the left ventricle) thins and stretches out of shape. The enlarged heart cannot pump blood effectively, which may eventually lead to heart failure. Symptoms include fatigue, weakness, shortness of breath, and swelling of the legs and feet. While up to a third of cases appear to be inherited, in most cases the cause remains unknown. However, many factors may contribute to dilated cardiomyopathy, including coronary artery disease, inborn heart defects, infections, toxins, drug or alcohol abuse, and some cancer drugs.

Unfortunately, dilated cardiomyopathy is often advanced by the time it is diagnosed and may be extremely debilitating. Losing weight (if needed) and limiting salt are often necessary, as are medications to help manage symptoms. A heart transplant can greatly improve survival, but the scarcity of donor hearts makes this option less common. Some people use small implanted mechanical pumps known as left ventricular assist devices, which take over part or all of the heart's pumping ability. In the past, such devices were used as a "bridge" to a heart transplant, but they are increasingly being used as a long-term solution.