Hypertrophic cardiomyopathy (HCM) is a condition where the heart muscle walls become thickened, which can make it more difficult for the heart to pump blood. Obstructive HCM is the most common type.

In obstructive HCM, the thickened heart walls reduce or block the blood flow from the left ventricle into the aorta.

Left untreated, it can lead to additional health problems, including blood clots, stroke, arrhythmias, heart failure, and sudden cardiac death.

This article reviews what obstructive HCM is and explores its possible symptoms, causes, complications, and more.

For more evidence-based information and resources for cardiovascular health, visit our dedicated hub.

Stethoscopes used for detecting obstructive hypertrophic cardiomyopathy.Share on Pinterest
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HCM is a heart condition where the walls of the heart chamber become thicker than is typical. This thickening can make the chamber stiff, which can result in restriction of blood flow in and out of the heart and increase the organ’s workload.

Obstructive HCM is the most common type. In obstructive HCM, the walls of the heart — usually the ventricular septum, which separates the two lower chambers — become too thick and restrict blood flow from the left ventricle to the aorta.

The condition may only partially block blood flow. However, it is a chronic condition that can get worse over time.

Vs. nonobstructive HCM

In nonobstructive HCM, the heart muscle has thickened without causing an obstruction or blocking the flow of blood.

Two-thirds of people with HCM have the obstructive type, and one-third have nonobstructive.

Symptoms of obstructive HCM can vary. Some people may not experience any, others may only feel them during exertion, and others may not develop them until later.

Common signs and symptoms of either type of HCM can include:

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Learn more about heart conditions and their symptoms.

In the vast majority of cases, there is a link between obstructive HCM and a certain type of genetic mutation in a person’s heart muscle proteins.

In other words, HCM is genetic, and a person may inherit it from their biological parents or relatives. Often, more than one family member develops the condition.

It is the most common genetic heart condition.

Learn more about congenital heart disease.

Obstructive HCM can lead to several potentially fatal complications, including:

Learn more

Learn more about emergency complications and how to manage them.

According to the American Heart Association (AHA), though HCM is present in children and adolescents, most people receive a diagnosis during middle age. It also states that while an estimated 1 in 500 people has either type of HCM, many never receive a diagnosis.

To diagnose the condition, a doctor will typically need to review a person’s medical history, perform a physical exam, and order a few tests.

Medical history

Reviewing a person’s medical history can help a doctor determine if obstructive HCM is likely based on their symptoms.

A doctor will likely want to know if a person’s parents may have had the condition. They may also ask if the person themselves currently has or has ever experienced other cardiovascular conditions.

The AHA recommends that the immediate family of a person who receives a diagnosis of obstructive HCM also undergo checkups to rule out the presence of the condition.

Physical exam

A doctor will likely need to perform a simple physical exam using a stethoscope to listen to the heart and lungs.

They may suspect obstructive HCM if any unusual sounds, such as swooshing, occur. A doctor will need to order other tests to confirm the presence of HCM.

Tests

Though several tests can help diagnose obstructive HCM, a cardiologist will likely use an echocardiogram to evaluate the heart’s thickness, valves, pumping strength, and whether or not obstruction is present.

Additional tests may include:

Treatment of obstructive HCM may consist of lifestyle changes, medications, and medical procedures.

Lifestyle changes

People without symptoms may benefit from lifestyle changes, such as:

Staying active may also be beneficial, but a person should discuss an appropriate exercise regimen with a physician. In some cases, doctors may advise against extreme exercise and competitive sports.

People with symptoms may need additional medications and medical procedures to help manage their symptoms.

Medication

For a person with HCM, a doctor may suggest the use of:

However, these can cause side effects. A person should let the prescribing doctor know if they develop any unusual symptoms after starting any medication.

If symptoms of HCM persist, doctors may prescribe Camzyos (mavacamten). This is a new medication that the FDA has approved specifically for people with obstructive HCM.

Procedures

Several procedures can help reduce the symptoms of obstructive HCM. Common procedures a doctor may recommend include:

  • A septal myectomy: This requires open heart surgery to reduce the size of the septum.
  • Alcohol septal ablation: This catheter-based procedure uses alcohol to kill some of the cells in the heart and reduce its thickness.
  • Cardiac implantable electronic devices: During an operation, surgeons may place a device called an implantable cardioverter-defibrillator to treat ventricular arrhythmias.
  • A heart transplant: Doctors typically only recommend replacing a person’s heart with a functioning one in the end stages of the condition.

For most people with obstructive HCM, the long-term outlook is very good. Many live healthy, complication-free lives.

A smaller number of people may develop more serious complications. The condition can result in sudden death in severe cases.

Outcomes can vary between family members. A person should work closely with a doctor or treatment team to monitor for signs of disease progression and to help manage risk.

Because obstructive HCM results from an inherited gene mutation, there is no way to prevent the condition from occurring.

However, a person can reduce their risk of complications by following a heart-healthy lifestyle. This may include the factors we describe above, such as managing weight and avoiding smoking.

The following sections provide answers to common questions about HCM.

At what age does obstructive HCM develop?

HCM can occur at any age. However, since many people do not have symptoms and because muscle thickening can occur later in the course of the condition, doctors often detect it in adolescence or adulthood.

In adults, diagnosis of the condition often does not occur until middle age.

How long can you live with obstructive HCM?

Most people live a typical life span with minimal complications.

A small number may experience complications, including sudden cardiac death.

Can I get pregnant if I have HCM?

People with obstructive HCM can get pregnant. However, they should discuss the potential risks for the pregnant person and the fetus with a cardiologist in advance.

Since obstructive HCM is genetic, people can pass it on to their children.

If a person with the condition decides to become pregnant and give birth, doctors will recommend screening the child for signs of HCM, and they may require lifelong monitoring for the development of the condition.

Obstructive hypertrophic cardiomyopathy (HCM) is a condition where the heart walls thicken and restrict blood flow between the left ventricle and the aorta.

Though it can lead to potentially fatal complications, many people with obstructive HCM have no symptoms and will not develop complications.

Lifestyle changes, such as dietary changes and regular exercise, may help treat symptoms and prevent complications. Medications and other interventions may also help treat symptoms of obstructive HCM.