Hypertrophic Cardiomyopathy

Hypertrophic cardiomyopathy is a heart condition where the muscle walls of the heart become thicker than normal. This can make it harder for the heart to pump blood and may cause symptoms like chest pain, shortness of breath or irregular heartbeats. It’s usually genetic, meaning it can run in families. Some people have no symptoms while others may need treatment to manage the condition.

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Comprehensive care for hypertrophic cardiomyopathy

Hypertrophic cardiomyopathy (HCM) is a common genetic disease where the heart muscle becomes abnormally thick, making it harder for the heart to pump blood. About 1 in 500 people have it, which adds up to 750,000 Americans — more than Boston’s entire population.

HCM can affect anyone, regardless of age, culture, race, ethnic group or gender. It often starts during puberty, but symptoms can appear or worsen at any age, typically in midlife. Some people may experience symptoms like shortness of breath, chest pain or fainting, while others may have no symptoms at all.

HCM is manageable with the right care. At Tufts Medicine, our expert team treats all types of HCM with compassion and expertise. We work with you to create a personalized care plan that fits your needs and lifestyle.

A Tufts Medical Center echocardiogram technologist explains the screen to Hypertrophic Cardiomyopathy Center (HCM) patient.

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Conditions

Hypertrophic cardiomyopathy (HCM) causes excessive thickening, or hypertrophy, of your heart muscle, making it challenging for the heart to pump blood to the rest of the body. It most commonly affects the septum, the muscular wall separating the left and right ventricles. The type of HCM you have — obstructive or nonobstructive — depends on whether the thickened muscle blocks or limits blood flow from the heart.

Obstructive HCM: About 2 out of 3 people with HCM have this type. In obstructive HCM, blood flow from the heart is partly blocked because the thickened heart muscle presses on the mitral valve. For some people, the blockage happens during exercise, while for others, it can happen even at rest. This blockage increases pressure in the heart and causes symptoms.
Nonobstructive HCM: About 1 in 3 people have this type. The heart muscle is still thickened, but there’s no blockage to blood flow. However, some people experience severe symptoms that aren’t fully controlled with medication, which can lead to heart failure over time.

HCM can also lead to other heart conditions like atrial fibrillation (AFib), heart failure and stroke. About 1 in 5 people with HCM develop AFib, which is a rapid and irregular heartbeat that increases the risk of stroke because blood clots can form and travel to the brain.

With the right care, HCM is manageable. At Tufts Medicine, our expert team provides personalized treatment to help you live your best life.

HCM symptoms

Not everyone with hypertrophic cardiomyopathy (HCM) has symptoms, and the severity can vary from person to person. When symptoms do appear, they may include:

Arrhythmia (irregular heartbeats)
Chest pain or pressure
Fatigue or excessive tiredness
Lightheadedness, dizziness or fainting
Loss of consciousness
Palpitations (sudden, forceful heartbeats)
Shortness of breath

If you notice any of these symptoms, it’s important to talk to your doctor right away. Early diagnosis and treatment can make a big difference in managing HCM.

Atrial fibrillation in HCM

About 1 in 5 people with HCM experience atrial fibrillation (AFib), an irregular and often rapid heartbeat.

AFib can affect your health in 2 major ways:

Frequent AFib episodes can lower your quality of life, causing symptoms like fatigue, shortness of breath and palpitations.
AFib increases the risk of stroke because it can lead to blood clots that travel to the brain.

Treatment options for AFib in HCM include antiarrhythmic medications to manage irregular heartbeat and a minimally invasive procedure called catheter ablation, which can help control AFib. To reduce the risk of stroke, doctors often prescribe blood thinners (anticoagulants), which are one of the most effective ways to prevent clots from forming.

If you have HCM and experience symptoms of AFib, talk to your doctor about treatment options that are best for you.

Testing

Although HCM is a genetic condition present at birth, many people don’t realize they have it until symptoms appear later in life. Regular physical exams are key to detecting HCM early and reducing the risk of severe symptoms.

In addition to a physical exam, we use the following cardiac imaging and noninvasive tests to confirm an HCM diagnosis:

Cardiac MRI + echocardiogram: These imaging tests provide detailed pictures of your heart to identify thickened heart muscle caused by HCM.
Electrocardiogram (EKG) + stress echocardiogram: These tests measure your heart’s electrical activity and assess how well your heart pumps blood, especially during physical activity.

Family screening + genetic testing

Hypertrophic cardiomyopathy (HCM) is linked to several gene mutations, and genetic testing may help determine if you carry one. People with HCM have a 50% chance of passing the condition to their children, so family screening is highly recommended. Early detection through family screening and genetic testing can help prevent severe symptoms and manage risks. If you have a family history of HCM, talk to your doctor about getting screened. This could protect both your health and your loved ones. Screening typically includes:

Cardiovascular imaging: Tests like echocardiograms or MRIs to check for heart muscle thickening.
Clinical evaluation: A complete heart health assessment and related symptoms.
Genetic testing (optional): A simple blood test to identify mutations linked to HCM.

While only 30% of people with HCM test positive for known mutations—since researchers are still discovering new ones—genetic testing can still provide valuable insights into your family’s risk, even if specific mutations are not detected.

Treatments

HCM is treatable, and most people won’t need surgery or major procedures. If you ever need advanced care, we’ll be here to answer your questions and support you every step of the way. Whether it's medication, minimally invasive procedures or more advanced treatments, we’ll work closely with you to find the best plan for your heart health. Our goal is to help you live a full and active life, with the right care and support tailored to your needs.

Monitoring

To monitor your HCM, it may be recommended that you wear an ambulatory ECG monitor. This small, wearable device checks your heart’s rhythm while you go about your normal activities. It records your heartbeats over time to help doctors find any unusual patterns or problems. Your doctor may recommend wearing it for one day or a few weeks.

We use this monitor to check for abnormal heart rhythms and see if they match symptoms of HCM like dizziness, a fast heartbeat or fainting.

Medications

Many people with HCM successfully control their symptoms for years or even decades with medication alone. Some of the most commonly prescribed medications for HCM include:

Anticoagulants (blood thinners): Help manage arrhythmia and atrial fibrillation.
Antiarrhythmic drugs: Help manage arrhythmia and atrial fibrillation.
Beta blockers: Help control additional symptoms.
Calcium channel blockers: Help control symptoms.
Disopyramide: Helps control obstructive HCM symptoms.

Heart failure caused by obstructive HCM can be permanently improved with medications like beta blockers, verapamil and disopyramide.

Minimally invasive procedures

When medications aren't enough to manage your symptoms, we may consider minimally invasive procedures, such as alcohol septal ablation or catheter ablation for recurrent AFib, to treat HCM. These procedures may also be recommended for older adults who haven't responded well to medication.

Alcohol septal ablation

Alcohol septal ablation is a procedure that helps reduce the thickness of the heart muscle and improve blood flow. It’s a good alternative to open-heart surgery, with fewer risks and complications.

This procedure is often recommended for older adults whose HCM symptoms don’t improve with medication.

Here’s how it works: A small tube (catheter) is placed into a blood vessel in your leg and guided to the heart. Once in place, a tiny balloon is inflated to block blood flow, and a small amount of alcohol is released into the heart to thin the muscle.

It can take a couple of weeks to see the full effects of the procedure.

Catheter ablation for recurrent atrial fibrillation (AFib)

A catheter ablation for AFib is done to reset your heart’s rhythm. It’s a procedure in which doctors use a small tube (catheter) to treat complex heart conditions with only a small incision.

This interventional cardiology procedure takes about 3–4 hours, and you’ll be under general anesthesia. During the procedure, tiny scars are created on your heart to help it beat normally. The catheters use two types of energy to create the scars:

Cryo (freezing energy)
Radiofrequency (heat energy)

Most people can return to normal activities within a few weeks after the procedure.

Potential interventions

While most people with HCM won’t need major surgery, some may need more advanced treatment to restore healthy heart function. When medications and other less invasive procedures don’t work, we may recommend one of the following interventions to help manage symptoms and improve your quality of life:

Heart transplant

If you have nonobstructive HCM and severe symptoms, we’ll first try treating you with medications. If they don’t work, a heart transplant may be considered. The good news is that survival rates with a heart transplant are high, with about 90% of people surviving for 5–10 years.

Implantable cardioverter defibrillator

A small number of people with HCM are at higher risk for life-threatening arrhythmias (heart rhythm problems). To prevent this, we can insert a device called an ICD (implantable cardioverter defibrillator) into the chest. The ICD sends electrical pulses to the heart to restore a healthy rhythm and prevent sudden cardiac arrest.

This device can help you return to the activities you enjoy and keep doing them for as long as you want.

Septal myectomy

A septal myectomy is an open-heart surgery that helps clear the obstruction in your heart, improve blood flow and reduce your HCM symptoms.

During the procedure, the doctor makes a small incision in the aorta to remove a small amount of muscle from the top of your septum wall. This helps restore your heart’s normal function.

The average hospital stay for this procedure is about 5 days, and full recovery takes several weeks.

FAQs

How did I get HCM? Did I do something wrong to cause it?

Hypertrophic cardiomyopathy is a genetic heart disorder. You were born with an abnormal gene that caused your heart muscle to thicken. Your heart muscle did not thicken due to poor lifestyle habits or anything else you may have done to yourself over the years. However, although you did nothing to cause it, maintaining a healthy lifestyle through weight and diet will absolutely benefit you in the long-run with respect to your symptoms and overall energy levels.

What is my life expectancy with HCM?

Most patients with hypertrophic cardiomyopathy can maintain an active lifestyle and have a normal lifespan. Mortality rates for HCM alone are only about 0.5% per year—which is no different than the general population for all causes. Most patients have near-normal life expectancies and live highly satisfying and productive lives.

Obstructive HCM sounds bad, should I worry?

Obstructive HCM refers to impeding blood flow out of the left lower chamber of the heart, which creates higher pressures. Obstruction is very common in HCM and is present in more than two-thirds of patients at rest and with physical activity. While some people develop symptoms secondary to obstruction and require septal myectomy (or alcohol ablation), many never develop symptoms throughout their entire lives.

Will my heart muscle continue to grow?

After full physical maturity, right after puberty, your heart muscle thickness usually stops increasing. For the vast majority, the thickness of the heart stays the same throughout the remainder of life.

My doctor recommends I get a septal myectomy. Will my heart muscle grow back?

No. Heart muscle cells do not regenerate and will not grow back after surgery.

Can I exercise with HCM?

Yes, a regular exercise routine has many psychological and physical benefits. Having HCM does not make you immune to developing coronary artery disease or having a heart attack (or other diseases related to leading a sedentary lifestyle). However, there are definitely activities to avoid. Intense physical exertion increases your heart rate and releases a rush of adrenaline that can predispose some individuals to heart arrhythmias. This places HCM patients at additional risk of passing out or sudden cardiac death. Exercise counseling should be individualized. Remember to talk to your doctor before starting any exercise program.

Which HCM signs should I notify my doctor about right away?

It is very important to call a doctor if you have persistent palpitations—heart flutters—that do not resolve with rest or if you have extreme lightheadedness or instances of fainting (syncope). Please also contact a doctor if your symptoms change or worsen despite rest. This could include increased shortness of breath, new chest discomfort, worsening fatigue or fluid retention. We're always here for you, so don't hesitate to reach out.