Hypertrophic cardiomyopathy (HCM) is the most common inherited cardiomyopathy (disease of the heart muscle). It affects as many as 1 in 500 people in the United States. Although it might not always cause problems in daily life, HCM is a serious condition. It can lead to many complications that can affect your quality of life and how long you live.

What Is Hypertrophic Cardiomyopathy?

HCM is a genetic disease caused by inherited gene mutations (changes) that result in left ventricular hypertrophy — when the left ventricle’s muscles become thick. HCM can make it difficult for the heart to pump properly, because it squeezes the inside of the left ventricle, making it smaller, and blocking the normal flow of oxygen-rich blood from the heart to the rest of the body.

HCM is a progressive disease, which means it can get worse over time, possibly leading to serious complications.

Symptoms of HCM can include:

• Shortness of breath
• Dizziness
• Heart palpitations (beating too fast, fluttering, or skipping a beat)
• Chest pain
• Fainting

Symptoms often appear only during exercise or strenuous physical activity. Some people with mild HCM may not have any significant symptoms. Those with severe HCM may experience symptoms even while resting.

6 Possible Complications of Hypertrophic Cardiomyopathy

Complications are medical problems associated with a disease. HCM can cause many complications, including arrhythmia (abnormal heartbeat), stroke, mitral valve disease, endocarditis, heart failure, dilated cardiomyopathy (the heart gets bigger and weaker), sudden cardiac arrest, and problems due to obstruction of blood flowing out of the heart.

1. Arrhythmia

Arrhythmias, abnormal heart rhythms, are a common complication of HCM. Several types of arrhythmia affect heart rate and heart function. Atrial fibrillation (AFib) is the most common arrhythmia that people with HCM may develop.

During AFib, the atria (smaller heart chambers) beat irregularly. This condition can cause:

• Heart palpitations
• Irregular heartbeat
• Shortness of breath
• Lightheadedness
• Fatigue (feeling extremely tired all the time, even after resting)
• Chest pain

AFib can also cause dangerous blood clots, which can lead to a stroke. Medications can control AFib, and anticoagulants (blood thinners) can help prevent blood clots from forming.

HCM rarely causes dangerous ventricular arrhythmias that need treatment. When the heart’s ventricles beat more than 100 times a minute for more than 30 seconds, it’s known as ventricular tachycardia. This rapid heartbeat can cause sudden death and is a serious condition that requires medical attention.

Your doctor may recommend changing your medication or placing an implanted cardioverter defibrillator — a device to monitor heart rhythm and deliver electric shocks as needed to correct dangerous irregular heartbeats.

2. Mitral Valve Disease

HCM can affect the heart’s mitral valve, which allows blood to flow from the left atrium into the left ventricle. HCM may cause abnormalities in the mitral valve that allow blood flow to move backward into the left atrium.

Mitral valve disease can cause a heart murmur without any symptoms, or it can cause fatigue, shortness of breath, and an irregular heartbeat. If your disease is severe, you may need surgery or a heart valve replacement.

3. Infective Endocarditis

Infective endocarditis (IE) is an infection of the lining of the heart, usually the heart valves. HCM affects the mitral valve, putting people with HCM at higher risk of IE of the mitral valve.

IE can happen when there’s damage to the tissue that covers the heart valves, making it more likely to become infected if there are bacteria in the bloodstream. IE can cause fever and symptoms of infection, along with chest pain and shortness of breath. These symptoms can also be caused by mitral valve dysfunction, when the valve between the heart’s left atrium and left ventricle doesn’t work properly.

Intravenous antibiotics, which are medicines delivered directly into a vein, can effectively treat IE. If damage to the mitral valve is severe, surgery may be needed to repair or replace the valve. Taking antibiotics before dental work can prevent IE by stopping bacteria from getting into the bloodstream.

4. Heart Failure

HCM rarely leads to heart failure, a condition that happens when damage to the heart makes it unable to provide oxygen-rich blood to the body. Heart failure can make you feel tired, short of breath, and have trouble breathing. It can also cause a cough, swelling in your legs, arrhythmia, and other symptoms.

Heart failure can be deadly, but it can often be managed by medication, surgery, or an implantable cardioverter defibrillator. Some people may need a heart transplant.

5. Dilated Cardiomyopathy

Some people with HCM may have dilated cardiomyopathy, which causes the heart’s ventricles to stretch out, making the chambers weak. This condition can make it harder for your heart to pump blood throughout your body.

At first, you might not realize you have dilated cardiomyopathy, but when symptoms show up, they can include fatigue or breathing difficulties. Sometimes, a test called an echocardiogram can find this condition, even in a person who hasn’t shown any symptoms. Luckily, dilated cardiomyopathy can be treated with medications or surgery.

6. Sudden Cardiac Death

Sudden cardiac death (SCD) — also called sudden cardiac arrest — rarely happens with HCM. However, some people with HCM are at higher risk. SCD can occur in young people — usually athletes — and in adults. Even if HCM is not causing any noticeable symptoms, it can increase the risk of SCD.

How Does Hypertrophic Cardiomyopathy Affect Life Expectancy?

HCM affects everyone differently. Studies have shown that people diagnosed with HCM have a high survival rate — a one-year survival rate of 98 percent and a 10-year survival rate of 75 percent.

In fact, many people with HCM never develop any symptoms, and it’s believed that many others with HCM are never diagnosed. Research suggests that most people with HCM have a normal life expectancy regardless of when HCM is diagnosed.

On the other hand, some people are at a higher risk of death due to complications from HCM. Risk factors for sudden cardiac death include a family history of sudden death and fainting as well blockages in the heart.

A dangerous irregular heartbeat called nonsustained ventricular tachycardia is also connected to a higher risk of heart-related death. Moderate to severe heart-function problems caused by heart failure also raises this risk. Talk to your cardiologist if you’re concerned about whether HCM may affect your life expectancy.

Living With Hypertrophic Cardiomyopathy

HCM affects people in various ways, and not knowing what to expect can feel overwhelming and scary when living with a long-term condition. But the good news is that HCM is a very treatable disease — and so are many of its complications. Learning more about HCM gives you the confidence to get help from your cardiology team and prevent any potential problems.

Talk With Others Who Understand

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