Types of Cardiomyopathy

Dilated Cardiomyopathy

Dilated cardiomyopathy is the most common type of the disease. It mostly occurs in adults aged 20 to 60. Men are more likely than women to have this type of cardiomyopathy.

Dilated cardiomyopathy affects the heart's ventricles (VEN-trih-kuls) and atria (AY-tree-uh). These are the lower and upper chambers of the heart, respectively.

The disease often starts in the left ventricle, the heart's main pumping chamber. The heart muscle begins to dilate (stretch and become thinner). This causes the inside of the chamber to enlarge. The problem often spreads to the right ventricle and then to the atria as the disease gets worse.

When the chambers dilate, the heart muscle doesn't contract normally. Also, the heart can't pump blood very well. Over time, the heart becomes weaker and heart failure can occur. Symptoms of heart failure include fatigue (tiredness); swelling of the ankles, feet, legs, and abdomen; and shortness of breath.

Dilated cardiomyopathy also can lead to heart valve problems, arrhythmias, and blood clots in the heart.

Hypertrophic Cardiomyopathy

Hypertrophic cardiomyopathy is very common and can affect people of any age. About 1 out of every 500 people has this type of cardiomyopathy. It affects men and women equally. Hypertrophic cardiomyopathy is the most common cause of sudden cardiac arrest (SCA) in young people, including young athletes.

This type of cardiomyopathy occurs when the walls of the ventricles (usually the left ventricle) thicken. Despite this thickening, the ventricle size often remains normal.

Hypertrophic cardiomyopathy may block blood flow out of the ventricle. When this happens, the condition is called obstructive hypertrophic cardiomyopathy. In some cases, the septum thickens and bulges into the left ventricle. (The septum is the wall that divides the left and right sides of the heart.) In both cases, blood flow out of the left ventricle is blocked.

As a result of the blockage, the ventricle must work much harder to pump blood out to the body. Symptoms can include chest pain, dizziness, shortness of breath, or fainting.

Hypertrophic cardiomyopathy also can affect the heart's mitral (MI-trul) valve, causing blood to leak backward through the valve.

Sometimes the thickened heart muscle doesn't block blood flow out of the left ventricle. This is called nonobstructive hypertrophic cardiomyopathy. The entire ventricle may become thicker, or the thickening may happen only at the bottom of the heart. The right ventricle also may be affected.

In both types (obstructive and nonobstructive), the thickened muscle makes the inside of the left ventricle smaller, so it holds less blood. The walls of the ventricle also may stiffen. As a result, the ventricle is less able to relax and fill with blood.

These changes cause increased blood pressure in the ventricles and the blood vessels of the lungs. Changes also occur to the cells in the damaged heart muscle. This may disrupt the heart's electrical signals and lead to arrhythmias.

Rarely, people who have hypertrophic cardiomyopathy have no signs or symptoms, and the condition doesn't affect their lives. Others have severe symptoms and complications, such as serious arrhythmias, an inability to exercise, or extreme fatigue with little physical activity.

Rarely, people who have this type of cardiomyopathy can have SCA during very vigorous physical activity. The physical activity can trigger dangerous arrhythmias. If you have this type of cardiomyopathy, talk to your doctor about what types and amounts of physical activity are safe for you.

Restrictive Cardiomyopathy

Restrictive cardiomyopathy tends to mostly affect older adults. In this type of the disease, the ventricles become stiff and rigid. This is due to abnormal tissue, such as scar tissue, replacing the normal heart muscle.

As a result, the ventricles can't relax normally and fill with blood, and the atria become enlarged. Over time, blood flow in the heart is reduced. This can lead to problems such as heart failure or arrhythmias.

Arrhythmogenic Right Ventricular Dysplasia

Arrhythmogenic right ventricular dysplasia (ARVD) is a rare type of cardiomyopathy. ARVD occurs when the muscle tissue in the right ventricle dies and is replaced with scar tissue.

This process disrupts the heart's electrical signals and causes arrhythmias. Symptoms include palpitations and fainting after physical activity.

ARVD usually affects teens or young adults. It can cause SCA in young athletes. Fortunately, such deaths are rare.