Many people with hypertrophic cardiomyopathy (HCM) don’t have symptoms or even know they have it. Heart murmurs are often found during physical exams for other reasons.

Although most people with HCM don’t have complications, some may develop serious complications, such as heart failure. Understanding what an HCM-related heart murmur is and what may be causing it can help you discuss treatment options with your doctor.

In this article, we’ll discuss what HCM-related heart murmurs are, how they’re diagnosed, and what they mean for your treatment. We’ll also discuss symptoms associated with HCM and when to seek medical attention.

How Heart Murmurs and HCM Are Connected

A heart murmur is an unusual sound your doctor may hear while listening to your heartbeat with a stethoscope. Not every murmur means something is wrong with your heart. Many heart murmurs are harmless and are called “innocent heart murmurs.”

Heart murmurs are often found during physical exams for other reasons.

Other murmurs are considered abnormal and may be a sign of a heart condition.

Abnormal heart murmurs are one possible sign of HCM. In HCM, the heart muscle becomes thickened, which can make it harder for your heart to pump blood. There are two main types of HCM: obstructive hypertrophic cardiomyopathy (oHCM) and nonobstructive HCM (nHCM).

In oHCM, the septum (the wall between the heart’s two lower chambers) becomes thickened. This can reduce blood flow from the left ventricle into the aorta (the main vessel that carries blood from your heart to the rest of your body). The resulting turbulence can cause the murmur often heard in people with oHCM.

What an HCM-Related Heart Murmur Sounds Like

During a normal heartbeat, your heart makes two sounds often described as “lub-DUB.” The “lub” sound (also called S1) occurs as valves close after the atria pump blood into the ventricles. The “DUB” sound (also called S2) occurs as valves close after the ventricles pump blood away from the heart.

In people with HCM, especially oHCM, the heartbeat can sound different.

Louder “Lub” Sound

For some people, the “lub” sound may sound louder than normal.

Murmur Between Heartbeat Sounds

People with oHCM often have a murmur that occurs between the two main heartbeat sounds (S1 and S2). This murmur is often described as a whooshing sound that gets louder and then quieter.

Abnormal heart murmurs are one possible sign of HCM.

This can happen when the wall between the heart’s two lower chambers thickens enough to partially block blood flow from the left ventricle to the aorta.

During an evaluation, your doctor may ask you to squat or raise your leg. These movements increase the amount of blood returning to the heart, so the left ventricle fills more fully. In HCM, this can make the murmur quieter.

If you stand, the left ventricle fills less fully, which can make the murmur louder. These changes in sound can help your doctor tell an HCM-related murmur apart from a murmur caused by aortic stenosis.

Additional Heart Sound

An extra sound can occur just before the first heartbeat sound of the next cycle. It can make the rhythm sound more like “ta-lub-DUB” and is often called the “S4 gallop.”

This can happen when blood is forced into a left ventricle that has become thickened and stiff because of HCM.

The S4 sound may give your doctor more information about how HCM is affecting your heart. A longer pause between the S4 sound and the next S1 sound may suggest a higher risk of heart problems and the need for more testing.

In one study, people with HCM who didn’t have an S4 sound had a higher risk of other heart problems, especially newly developed atrial fibrillation.

How Doctors Diagnose Murmurs in People With HCM

If you think you may have HCM, your healthcare provider will start with a physical exam. During this exam, they’ll listen to your heart and lungs with a stethoscope to check for murmurs. Heart murmurs are sometimes found during physical exams for other reasons as well.

HCM is often caused by inherited gene changes. Because HCM can run in families, your doctor will ask whether you have a family history of HCM or whether any family members have other heart problems.

In people with HCM, especially oHCM, changes in the heartbeat can create sounds your doctor may hear as a murmur.

Close relatives of someone diagnosed with HCM may want to be screened for the disease. Genetic testing can help identify gene changes linked to HCM and can guide care for you and your family.

If your doctor detects a heart murmur or suspects you have HCM based on other symptoms, they may run the tests below to confirm the diagnosis.

Electrocardiogram

An electrocardiogram (ECG or EKG) uses electrodes placed on the chest and sometimes on the arms and legs to measure the heart’s electrical activity.

An electrocardiogram can detect irregular heartbeats and signs of heart muscle thickening. This test is quick and painless.

Echocardiogram

An echocardiogram is another common test used to diagnose HCM. It uses sound waves to create moving images of the heart. These images can show whether the heart walls are thickened and how well the heart is pumping blood.

Cardiac MRI

A cardiac MRI uses magnetic fields and radiofrequency waves to produce images of your heart. This test can show how well the heart and valves are working. A cardiac MRI is often done in addition to an echocardiogram.

Stress Test

A stress test can measure how well your heart handles physical activity. This test usually involves walking on a treadmill or riding an exercise bike, but if you’re unable to exercise, medication may be used to simulate the effects of exercise instead.

Stress tests may be performed with ECG monitoring, nuclear heart scanning, positron emission tomography (PET) scanning, or an echocardiogram.

Holter and Event Monitors

These monitors can detect arrhythmias (unusual heart rhythms) and record your heart’s activity over time. Some monitors, such as Holter monitors, are worn for one or two days while you do your regular activities.

What an HCM Murmur Can Mean for Treatment and Monitoring

A heart murmur can be an early sign of HCM. Although there’s no known way to prevent HCM, there are ways to manage this lifelong condition. Early detection helps healthcare professionals guide treatment and prevent complications.

If HCM is causing the murmur, treating HCM may help reduce symptoms and lower the risk of complications.

Treatment can involve:

• Monitoring — Regular tests such as ECGs and echocardiograms can help monitor your condition.
• Medications — Medications such as beta-blockers, calcium channel blockers, and myosin inhibitors (a newer class of drugs that reduce the heart muscle’s excessive contractions) may help improve symptoms.
• Procedures — Options can include septal myectomy (surgery to remove part of the thickened heart wall), cardiac implantable electronic devices (such as implantable cardioverter defibrillators and pacemakers), a heart transplant (in advanced cases), and a nonsurgical procedure called alcohol septal ablation.

Lifestyle changes, such as eating a heart-healthy diet, quitting smoking, staying active as recommended by your healthcare provider, and getting good sleep, are also recommended.

When To Call the Doctor About a Heart Murmur

Often, people with HCM don’t have symptoms or even know they have it. Most people don’t feel symptoms from a heart murmur itself. However, the underlying cause of the murmur can cause symptoms.

With HCM, you may experience the following:

• Dizziness
• Chest pain, often with exercise
• Fainting
• Fatigue or shortness of breath, often with exercise
• Rapid heart rate or pounding heartbeats

Although other conditions can cause these symptoms, it’s important to have a checkup to find the cause and get the right care. HCM can cause life-threatening health problems in some people. If you’ve been diagnosed with HCM, it’s important to see a cardiologist regularly.

If you have any of the symptoms below for more than a few minutes, call 911 (or your local emergency number):

• Chest pain
• Difficulty breathing
• Heartbeat that is fast or irregular

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