Definition and Overview

Hypertrophic cardiomyopathy (HCM) is a heart disease that occurs when the heart muscle becomes thick. It is a genetic or inherited disease. This means that it is passed on through a parent’s genes. A person has a 50% chance of inheriting the disease if at least one of his or her parents has it.

HCM affects one in every 500 people. However, it is not always a cause for concern. Many who have it do not have symptoms and live normal, active lives. However, about 10% suffer from severe cases and have an increased risk of arrhythmias (abnormal heart rhythm) and sudden cardiac death.

HCM can make it difficult for the heart to pump blood properly. Because of this, the amount of blood that circulates the body can be reduced. When this happens, vital organs, such as the brain and the lungs, may not receive enough supply of oxygen and nutrients they need to work properly.

HCM can be obstructive or non-obstructive. In some people, it causes the wall that separates the heart’s ventricles (septum) to enlarge. This makes it difficult for the heart to push the blood out to the lungs (obstructive). In other cases, the disease affects the right ventricle in a way that it can only hold a small amount of blood. Thus, even when there is no obstruction, the amount of blood that reaches the vital organs is still reduced.

Causes of Condition

HCM is an inherited condition. People who have it have a 50% chance of passing it to their children. As such, people with close relatives (such as a parent or a sibling) who have the condition are advised to undergo HCM screening. The disease can be caught early. It can also be treated before symptoms appear. Early diagnosis allows patients to better understand the disease. This can also help them prevent it from getting worse. One way to prevent the disease from progressing is to avoid competitive sports.

With early treatment and some lifestyle changes, most patients are able to live normal lives. They are also able to control their symptoms.

Key Symptoms

HCM does not always cause symptoms. If it is mild, patients can go on with their lives without knowing they have it. However, more serious cases can cause shortness of breath and chest pain. These can become more noticeable during heavy exercise and competitive sports. Other symptoms include fainting and dizziness.

HCM can lead to a number of complications if left untreated. These include:

  • Heart failure - A thickened heart muscle can cause the heart to fail. This can cause death in some cases.

  • Irregular heartbeats - The normal heart rate for adults is between 60 and 100 beats per minute. HCM can make the heart beat too fast or too slow (arrhythmias). This can cause a person to feel like their heart is racing or fluttering. Some types of arrhythmias are not a cause for concern. Others, on the other hand, can increase the risk of blood clots. If a blood clot gets dislodged and travels to a brain artery, the patient may suffer from a stroke. Certain arrhythmias can also cause sudden cardiac death.

  • Mitral valve regurgitation - In normal circumstances, the blood travels in one direction as it enters any type of blood vessel. However, HCM can prevent the mitral valve from closing properly. This causes the blood to flow back. When this happens, the symptoms are more likely to get worse.

Who to See and Types of Treatments Available

A person showing signs of HCM must consult a heart specialist. The same is advised for those with a family history of the disease. Tests used to diagnose HCM are:

  • Echocardiogram - Also called an echo, this is an ultrasound test of the heart. It uses sound waves to create pictures of the heart. It also takes pictures of the heart’s valves, walls, and chambers as well as blood vessels. It is not invasive and does not require numbing drugs. It uses a probe that is passed over the chest while the person is lying on his back or side. If abnormalities are found, this test is followed by a cardiac MRI (magnetic resonance imaging). This test also creates images of the heart. But it provides more detailed information. As such, it is used by doctors to make a definitive diagnosis.

  • Electrocardiogram - Also known as ECG, this test is used to measure the heart’s electrical impulses. This is often performed with a treadmill stress test.

  • Cardiac catheterisation

When treating HCM, doctors focus on improving heart function and stabilising heart rhythm using medications or a pacemaker. These treatments can relieve the symptoms of the disease. They can also prevent complications, such as heart failure and sudden cardiac death.

A procedure called septal ablation may also be necessary. It is advised if a part of the thickened heart muscle has to be removed to improve symptoms. Some patients may also need open-heart surgery. This is advised if a part of the thickened septum has to be removed to restore normal blood flow. This can also prevent blood from flowing back to the heart.


  • Gersh BJ, et al. 2011 ACCF/AHA guideline for the diagnosis and treatment of hypertrophic cardiomyopathy: Executive summary: A report of the American College of Cardiology Foundation/American Heart Association Task Force on Practice Guidelines.

  • Prevention and treatment of cardiomyopathy. American Heart Association.

  • Dearani JA, et al. Surgery insight: Septal myectomy for obstructive hypertrophic cardiomyopathy — The Mayo Clinic experience. Nature Clinical Practice Cardiovascular Medicine. 2007;4:503.

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