In some cases, hypertrophic cardiomyopathy (HCM) does not cause any symptoms. People with HCM are generally able to lead typical lives. However, some cases can become very serious. Serious cases may develop either slowly or suddenly.

HCM affects about 0.2 percent of the population in the United States. This is about 750,000 people.

HCM is a condition in which your heart muscle, or myocardium, becomes thicker than usual. This interferes with your heart’s ability to pump blood and to relax.

The condition can cause different effects in people. Some of the changes to the heart that doctors may identify include:

  • Septal hypertrophy. This is the thickening of the heart’s walls, which means the heart needs more force to pump. Hypertrophy can also happen in other parts of the heart.
  • Mitral leaflet abnormalities. These are changes to the four flaps that come together to close the mitral valve so blood keeps moving forward in the heart.
  • Mitral regurgitation. This generally occurs as a result of a suction effect (known as the Venturi effect) that can cause blood to backflow in the heart. As a result, you can feel short of breath and fatigued.
  • Problems with blood leaving the heart. Also known as left ventricular outflow tract obstruction, these are changes to the heart that keep blood from leaving and going to the rest of the body.
  • Arrhythmia. An irregular or fluttering heartbeat is a common side effect of HCM.
  • Relaxation abnormalities. Thickening of the heart muscle that occurs along with HCM can cause a sluggish or irregular heartbeat.

While an older person with heart disease can experience these symptoms, those with HCM experience them unexpectedly and sometimes at a young age.

In hearts affected by HCM, you'll find a smaller left ventricle and a thickened ventricular septum.Share on Pinterest
Illustration by Wenzdai Figueroa

Many people with HCM do not experience any symptoms. However, the following symptoms may occur during physical activity:

Other symptoms that might occur at any time include:

HCM is typically an inherited condition, but in some cases, the cause of HCM is never identified.

Genetics

Mutated genes can cause your heart muscle to thicken. Doctors have identified mutations in more than 15 different genes that may cause HCM.

HCM follows a dominant pattern of inheritance. This means if you inherit one gene associated with the condition, you could have symptoms. But inheriting the gene does not necessarily mean you’ll have symptomatic disease.

If you have a family history of HCM or have the condition yourself, you can talk with a genetic counselor about testing. Genetic testing could help you identify if you are a carrier for the HCM mutation (even if you don’t have symptoms) or your likelihood of passing the condition on to another generation.

Other causes

Other possible causes of HCM include aging and high blood pressure. Some increase in blood pressure can be expected as you get older, but this can also lead to more serious conditions, like HCM.

Doctors estimate only a small fraction of people with HCM actually receive a diagnosis for their condition. Some people receive a diagnosis when they’re having imaging studies done for something else and a doctor notices an atypical characteristic.

Doctors can use different tests to diagnose HCM:

  • Physical exam. During this exam, your doctor will listen for a heart murmur or unusual heartbeats. Heart murmurs may occur if a thickened heart muscle disrupts blood flow to your heart.
  • Echocardiogram. This is the most common diagnostic test for HCM. An echocardiogram creates images of your heart using sound waves. Your doctor will look for any unusual movements.
  • Electrocardiogram. An electrocardiogram measures the electrical activity in your heart. HCM can cause atypical results.
  • Holter monitor. A Holter monitor is a portable electrocardiogram that you can wear throughout the day. You may wear it for 24 to 48 hours or up to 1 month. This allows your doctor to see how your heartbeat changes during different activities and if you’re at risk for sudden cardiac death.
  • Cardiac MRI. A cardiac MRI uses a magnetic field to produce detailed images of your heart.
  • Cardiac catheterization. This test measures the pressure of blood flow in your heart and looks for blockages. Your doctor will place a catheter in one of the arteries in your arm or near your groin. The catheter is carefully threaded up through your artery to your heart. Once it reaches your heart, dye is injected so your doctor can take detailed X-ray images.

Treatment for HCM focuses on relieving symptoms and preventing complications, especially sudden cardiac death. The methods used depend on your:

  • symptoms
  • age
  • activity level
  • heart function
  • outflow obstruction

Medications

If you have HCM symptoms, your doctor will usually prescribe beta-blockers and calcium channel blockers. These medications relax your heart muscle. Relaxation helps it work better.

If you have an irregular heart rhythm, your doctor might prescribe antiarrhythmic medications, such as:

More recently, researchers have investigated a drug called mavacamten (MyoKardia) for its use in treating people who have symptomatic cardiomyopathy. Researchers in human trials found the medication reduces symptoms and improves physical functioning. The medication works by inhibiting cardiac myosin, a protein in the heart involved in contraction (squeezing).

Septal myectomy

A septal myectomy is an open-heart surgery that’s done to remove part of your thickened septum. The septum is the heart muscle wall between your two lower heart chambers (ventricles). It helps improve blood flow through your heart.

A septal myectomy is done only if medications do not reduce your symptoms.

Septal ablation

Septal ablation involves the use of alcohol to destroy part of your thickened heart muscle. The alcohol is injected through a catheter placed in the artery that supplies it to the part of your heart that’s being treated.

A septal ablation is often done in people who cannot have a septal myectomy.

Pacemaker implantation

If you have an irregular heart rate and rhythm, a tiny electronic device called a pacemaker can be placed under the skin on your chest. The pacemaker helps regulate your heart rate by sending regulated electrical signals to it.

Implantable cardioverter defibrillator

An implantable cardioverter defibrillator (ICD) is a small device that uses electric shocks to track your heartbeat and fix dangerous, atypical heart rhythms. It’s placed inside your chest.

ICD is often used in people who have a high risk of sudden cardiac death.

Lifestyle changes

If you have HCM, your doctor may recommend lifestyle changes to reduce your risk of complications. These include:

Can HCM be cured?

There is currently no cure for HCM. However, many individuals with the condition experience mild symptoms or none at all.

For those who do experience symptoms, treatments are available, ranging from medications to surgery. The key is receiving a diagnosis for the condition so you can start treatment.

The outlook for HCM has dramatically improved. As little as 35 years ago, the mortality rates for HCM were 6 percent per year. Today, these rates are estimated at 0.5 percent per year.

Many people with HCM may never have any serious health problems caused by it. However, HCM can cause severe complications in some people. The most common complications of HCM are:

Sudden cardiac arrest

Sudden cardiac arrest occurs when your heart suddenly stops working. This condition is also called “sudden cardiac death.”

This is typically caused by a rapid heart rhythm known as ventricular tachycardia. Without emergency treatment, sudden cardiac arrest can be fatal.

HCM is the leading cause of sudden cardiac death in people who are under 30 years old. This could manifest in an athlete with undiagnosed HCM who experiences sudden cardiac death on the playing field.

You might be at a higher risk for sudden cardiac death if you have one or more of the following:

  • a family history of sudden cardiac death
  • inadequate heart function
  • severe symptoms
  • a history of irregular heart rhythms with a fast heart rate
  • a history of fainting on several occasions and you’re young
  • an unusual blood pressure response to physical activity

The longer you live with HCM, the less likely you are to die from sudden cardiac death.

According to the New England Journal of Medicine, people older than age 70 have a 0.2 percent risk for sudden cardiac death. This rate is similar to that of individuals the same age who do not have HCM.

Heart failure

When the heart doesn’t pump the amount of blood the body needs, this is known as heart failure. Medications may help to reduce heart failure symptoms and the chest pain that can commonly occur with this condition.

Getting support

Having a disease like severe HCM can raise your risk of emotional challenges. Some people have trouble coping with the adjustments they have to make, such as restricting exercise and relying on medication for the rest of their lives.

If you’re having difficulty coping with HCM, your doctor might recommend seeing a therapist or joining a support group. The Hypertrophic Cardiomyopathy Association also offers support from nurse navigators who can help you receive free support for your condition.

You might also benefit from medications used to treat anxiety or depression.

HCM is a genetic, lifelong disease. In some people, it can contribute to early death and disability.

New treatments and medications may potentially extend the life and daily functioning of those with symptomatic HCM.