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Hypertrophic Cardiomyopathy


Tisha Suboc

, MD, Rush University

Reviewed/Revised Jan 2024
Topic Resources

Hypertrophic cardiomyopathy includes a group of heart disorders in which the walls of the ventricles (the 2 lower chambers of the heart) thicken (hypertrophy) and become stiff.

  • Most cases of hypertrophic cardiomyopathy are caused by an inherited genetic defect.

  • People experience fainting, chest pain, shortness of breath, and palpitations (awareness of irregular heartbeats).

  • Doctors suspect the diagnosis based on physical examination findings, but they use echocardiography or magnetic resonance imaging to confirm the diagnosis.

  • Medications that reduce the force of the heart’s contractions are given.

The Heart

The term cardiomyopathy is most often used when a disorder directly affects the heart muscle. Other disorders, such as high blood pressure and abnormal heart valves (such as aortic stenosis), also can eventually cause thickened heart muscle and heart failure.

Causes of Hypertrophic Cardiomyopathy

Hypertrophic cardiomyopathy is nearly always caused by a genetic defect. The defect may be a

  • Spontaneous genetic mutation

  • Inherited genetic defect


The thick, stiff walls of the ventricles do not relax appropriately to allow the heart chambers to fill with blood. This difficulty becomes more severe when the heart beats quickly (as during exercise) because there is then even less time for the heart to fill. Because the heart does not fill properly, it pumps less blood with each beat. Sometimes the thickened heart walls also interfere with blood flow out of the heart. This variation is called hypertrophic obstructive cardiomyopathy.

Because the ventricle walls thicken, the mitral valve (the valve that opens between the left atrium and the left ventricle) may be unable to close normally, resulting in leakage of blood back into the left atrium (mitral regurgitation Mitral Regurgitation Mitral regurgitation is leakage of blood backward through the mitral valve each time the left ventricle contracts. Disorders directly affecting the mitral valve and heart attack are the most... read more Mitral Regurgitation ). This valve leakage and the enlarged ventricular walls typically cause abnormal heart sounds (heart murmurs).

Symptoms of Hypertrophic Cardiomyopathy

Symptoms are highly variable, but when they occur, they usually develop when people are between ages 20 and 40 years. Symptoms first occur during exercise and include

  • Fainting (syncope)

  • Chest pain

  • Shortness of breath

  • Sensation of irregular heartbeats (palpitations)

Fainting usually occurs suddenly without any warning symptoms. Fainting or even sudden death may be the first sign that a person has this condition.

Diagnosis of Hypertrophic Cardiomyopathy

  • Echocardiography and/or magnetic resonance imaging (MRI) of the heart

Doctors usually suspect the diagnosis of hypertrophic cardiomyopathy based on the person's symptoms and the results of a physical examination, electrocardiography (ECG), and a chest x-ray. The heart sounds and any murmurs heard through a stethoscope may be helpful. Although ECG and echocardiography are not recommended for all young competitive athletes, all such athletes should be evaluated Sudden Cardiac Death in Athletes An estimated 1 to 3 per 100,000 apparently healthy young athletes develop an abrupt-onset heart rhythm abnormality and die suddenly during exercise. Males are affected up to 10 times more often... read more for risk factors that indicate the need for further testing.

Cardiac catheterization Cardiac Catheterization and Coronary Angiography Cardiac catheterization is a procedure that can measure heart function through a catheter inserted into a vein or artery and guided into the heart. Coronary angiography, which can be done during... read more Cardiac Catheterization and Coronary Angiography , an invasive procedure in which a catheter is threaded from a blood vessel in the arm, neck, or leg into the heart, is often done to measure pressures in the heart chambers and the degree to which blood flow from the left ventricle is blocked due to the thickened walls.

Because hypertrophic cardiomyopathy is usually caused by a gene mutation, genetic testing may also be done to help identify affected relatives.

Treatment of Hypertrophic Cardiomyopathy

  • Medications such as a beta-blocker and/or a calcium channel blocker

  • Sometimes a procedure to improve blood flow

  • Sometimes an implantable cardioverter-defibrillator

If possible, doctors treat the condition causing hypertrophic cardiomyopathy.

Treatment of hypertrophic cardiomyopathy is aimed primarily at reducing the heart’s resistance to filling with blood between heartbeats.

Medications for hypertrophic cardiomyopathy

Beta-blockers and the calcium channel blocker verapamil—taken separately or together—are the main treatment. Both reduce the force of heart muscle contraction. As a result, the heart can fill better and, if the thickened muscle was blocking blood flow, blood can flow out of the heart more easily. Also, beta-blockers and verapamil slow the heart rate, so that the heart has more time to fill. Sometimes, disopyramide, a medication that decreases the strength of heart contractions, is also used.

Amiodarone is sometimes used to treat abnormal heart rhythms.

Mavacamten decreases the contraction of the heart and seems to relieve symptoms and increase exercise tolerance.


Surgery to remove some of the thickened heart muscle (myectomy) can improve the flow of blood from the heart, but surgery is done only when symptoms are incapacitating despite medication. Myectomy can relieve symptoms, but it does not reduce the risk of death. When myectomy is done in hospitals that have extensive experience doing the procedure, long-term results are excellent.

Alcohol ablation

Alcohol ablation (controlled destruction of a small area of heart muscle by injecting it with alcohol) is used in certain people to improve blood flow from the heart because it can be done during cardiac catheterization Cardiac Catheterization and Coronary Angiography Cardiac catheterization is a procedure that can measure heart function through a catheter inserted into a vein or artery and guided into the heart. Coronary angiography, which can be done during... read more Cardiac Catheterization and Coronary Angiography . Although cardiac catheterization is an invasive procedure in which a catheter is threaded into the heart, it has fewer risks in people who are at high risk of complications if they have heart surgery.

Implantable cardioverter-defibrillator

People who have severe heart muscle thickening, especially thickening of the wall that separates the heart chambers (cardiac septum), have a high risk of developing deadly abnormal heart rhythms which cause sudden death. Doctors may recommend an implantable cardioverter-defibrillator Cardioversion-Defibrillation There are many causes of abnormal heart rhythms (arrhythmias). Some arrhythmias are harmless and do not need treatment. Sometimes arrhythmias stop on their own or with changes in lifestyle,... read more Cardioversion-Defibrillation for these people.

Prognosis for Hypertrophic Cardiomyopathy

About 1% of adults with hypertrophic cardiomyopathy die each year. Children with hypertrophic cardiomyopathy are more likely to die than adults.

Other factors that suggest a greater risk of death include the following:

  • Family history of sudden death, particularly premature sudden death

  • Unexplained fainting

  • Occurrence of rapid and certain abnormal heart rhythms

  • Cardiac arrest

  • Severity of thickening in the heart muscle

  • Severe inability of the heart to pump enough blood

  • Characteristic MRI appearance

People who learn that they have inherited this disorder should have genetic counseling when they plan a family because they have a 50% chance of passing this disorder on to their offspring. First-degree family members (siblings or children) of people who have this inherited disorder should have their heart evaluated (with either genetic testing and/or routine echocardiography).

More Information

The following English-language resource may be useful. Please note that THE MANUAL is not responsible for the content of this resource.

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