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Hypertrophic cardiomyopathy (HCM) is a condition in which the heart muscle becomes thick. Often, only one part of the heart is thicker than the other parts.
The thickening can make it harder for blood to leave the heart, forcing the heart to work harder to pump blood. It also can make it harder for the heart to relax and fill with blood.
Cardiomyopathy - hypertrophic (HCM); IHSS; Idiopathic hypertrophic subaortic stenosis; Asymmetric septal hypertrophy; ASH; HOCM; Hypertrophic obstructive cardiomyopathy
Hypertrophic cardiomyopathy is a condition that is usually passed down through families (inherited). It is believed to be a result of several problems (defects) with the genes that control heart muscle growth.
Younger people are likely to have a more severe form of hypertrophic cardiomyopathy. However, the condition is seen in people of all ages.
Some patients have no symptoms. They may not even realize they have the condition until it is found during a routine medical exam.
The first symptom of hypertrophic cardiomyopathy among many young patients is sudden collapse and possible death. This can be caused by very abnormal heart rhythms (arrhythmias), or from the blockage of blood from the heart to the rest of the body.
Common symptoms include:
Exams and Tests
The health care provider will perform a physical exam and listen to the heart and lungs with a stethoscope. Signs may include:
- Abnormal heart sounds or a heart murmur. These sounds may change with different body positions.
- High blood pressure
The pulse in your arms and neck will also be checked. The doctor may feel an abnormal heartbeat in the chest.
Tests used to diagnose heart muscle thickness, problems with blood flow, or leaky heart valves (mitral valve regurgitation) may include:
- 24-hour Holter monitor (heart rhythm monitor)
- Cardiac catheterization
- Chest x-ray
- Echocardiography (the most common test) to diagnose and follow the condition
- MRI of the heart
- Transesophageal echocardiogram (TEE)
Blood tests may be done to rule out other possible diseases.
Close family members of people who have been diagnosed with hypertrophic cardiomyopathy may be screened for the condition.
If you have hypertrophic cardiomyopathy, always follow your doctor's advice about exercise and medical appointments. You may be advised to avoid strenuous exercise.
If you have symptoms, you may need medication to help the heart contract and relax correctly. These may relieve chest pain or shortness of breath when exercising. Some medications used include beta-blockers and calcium channel blockers.
Some people with arrhythmias may need treatment, such as:
- Medicines to treat the abnormal rhythm
- Blood thinners to reduce the risk of blood clots (if the arrhythmia is due to atrial fibrillation)
- A permanent pacemaker to control the heartbeat
- An implanted defibrillator that recognizes life-threatening heart rhythms and sends an electrical pulse to stop them. Sometimes a defibrillator is placed, even if the patient has not had an arrhythmia, but is at high risk for a deadly arrhythmia (for example, if the heart muscle is very sick or the patient has a relative who has died suddenly).
When blood flow out of the heart is severely blocked, symptoms can become severe. An operation called surgical myectomy may be done. In some cases, patients may be given an injection of alcohol into the arteries that feed the thickened part of the heart (alcohol septal ablation). Patients who have this procedure often show significant improvement.
If the heart's mitral valve is leaking, surgery may be done to repair or replace the valve.
Some people with hypertrophic cardiomyopathy may not have symptoms and will have a normal lifespan. Others may get worse slowly or quickly. The condition may develop into dilated cardiomyopathy in some patients.
People with hypertrophic cardiomyopathy are at higher risk for sudden death than the normal population. Sudden death can occur at a young age.
Hypertrophic cardiomyopathy is a well-known cause of sudden death in athletes. Almost half of deaths in hypertrophic cardiomyopathy happen during or just after the patient has done some type of physical activity.
When to Contact a Medical Professional
Call for an appointment with your health care provider if:
- You have any symptoms of hypertrophic cardiomyopathy
- You develop chest pain, palpitations, faintness, or other new or unexplained symptoms
Maron BJ. Hypertrophic cardiomyopathy. Bonow RO, Mann DL, Zipes DP, Libby P, eds.Braunwald's Heart Disease: A Textbook of Cardiovascular Medicine. 9th ed. St. Louis, Mo: WB Saunders; 2011:chap 69.
Reviewed By: Michael A. Chen, MD, PhD, Assistant Professor of Medicine, Division of Cardiology, Harborview Medical Center, University of Washington Medical School, Seattle, Washington. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M. Health Solutions, Ebix, Inc.