Hypertrophic cardiomyopathy (HCM) is very common and can affect people of any age. About one out of every 500 people has HCM. It affects men and women equally.
HCM is a common cause of sudden cardiac arrest (SCA) in young people, including young athletes.
HCM occurs if heart muscle cells enlarge and cause the walls of the ventricles (usually the left ventricle) to thicken. Despite this thickening, the ventricle size often remains normal. However, the thickening may block blood flow out of the ventricle. If this happens, the condition is called obstructive hypertrophic cardiomyopathy.
Sometimes, the septum thickens and bulges into the left ventricle. This also can block blood flow out of the left ventricle. (The septum is the wall that divides the left and right sides of the heart.) If a blockage occurs, the ventricle must work hard to pump blood to the body. Symptoms can include chest pain, dizziness, shortness of breath, or fainting.
HCM also can affect the heart's mitral 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 non-obstructive hypertrophic cardiomyopathy. The entire ventricle may thicken, or the thickening may happen only at the bottom of the heart. The right ventricle also may be affected.
In both types of HCM (obstructive and non-obstructive), 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 can raise 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.
Some people who have HCM have no signs or symptoms. The disease doesn't affect their lives. Others have severe symptoms and complications. For example, they may have shortness of breath, serious arrhythmias, or an inability to exercise.
Rarely, people who have HCM can have SCA during very vigorous physical activity. The physical activity can trigger dangerous arrhythmias. If you have HCM, ask your doctor what types and amounts of physical activity are safe for you.
Other Names for Hypertrophic Cardiomyopathy
- Asymmetric septal hypertrophy
- Familial hypertrophic cardiomyopathy
- Hypertrophic nonobstructive cardiomyopathy
- Hypertrophic obstructive cardiomyopathy
- Idiopathic hypertrophic subaortic stenosis (IHSS)
What causes hypertrophic cardiomyopathy?
Hypertrophic cardiomyopathy (HCM) usually is inherited. It's caused by a mutation (change) in some of the genes in heart muscle proteins. HCM also can develop over time because of high blood pressure or aging.
Other diseases, such as diabetes or thyroid disease, also can cause HCM. Sometimes the cause of the disease isn't known.
Other Type of Cardiomyopathy:
- What is Cardiomyopathy in Adults?
- Understand Your Risk for Cardiomyopathy
- Symptoms and Diagnosis of Cardiomyopathy
- Prevention and Treatment of Cardiomyopathy
- Cardiomyopathy in Children