Heart Disease Information/General Information

HCM and Sudden Death: Risk Factors and Prevention

Medically reviewed by Vedran Radonić, M.D., Ph.D.

Written by Sherri Gordon, CLC

Posted on June 12, 2026

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Key Takeaways

Hypertrophic cardiomyopathy, or HCM, is a genetic heart condition that affects about 1 in 500 people and can raise the risk of sudden cardiac death, though many people do not know they have it until a serious heart event occurs.

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Hypertrophic cardiomyopathy (HCM) is a serious heart condition that affects about 1 in 500 people and can raise the risk of sudden cardiac death (SCD). Many people, including young athletes, don’t even know they have HCM until a serious heart problem happens.

Fortunately, there are ways to lower the risk of SCD, but first, you need to know whether you have HCM. That’s why it’s so important to be screened if you have a parent or sibling with the condition. If one of your parents has HCM, you have a 50 percent chance of inheriting the mutation (gene change) that causes it.

Here’s what you need to know about HCM and sudden death. You’ll also find information on HCM risk factors as well as how to reduce the risk of SCD.

How Can HCM Lead to Sudden Cardiac Death?

Hypertrophic cardiomyopathy is a genetic heart condition that causes your heart muscle to get bigger and thicken. This thickening can make it harder for your heart to pump blood.

Some people with HCM never have symptoms or know they have the condition. Others may have chest pain, shortness of breath, or other signs of HCM.

HCM can affect the heart’s electrical signals and may lead to a fast, irregular heart rhythm. In rare cases, this rhythm can become life-threatening and lead to sudden cardiac death.

Although sudden cardiac death from HCM is rare, HCM is still considered the most common cause of sudden cardiac death in young athletes and adults under 35. Many of those who do experience sudden cardiac death didn’t have any symptoms.

Interestingly, one study found that most cases of sudden cardiac death happened while people were resting or doing gentle exercise. Only about 17 percent of the deaths happened during competition or physical activity.

The good news is that there are medications and procedures to treat HCM that can help you live just as long as people who don’t have the condition. The key is knowing your family history and getting a diagnosis early if you’re at increased risk.

What Are the Top Risk Factors for Sudden Cardiac Death?

One of the biggest predictors of your risk for sudden cardiac death is your family history. In fact, one study found that your risk of SCD increases by 20 percent if someone else in your family experienced sudden cardiac death.

For this reason, let your healthcare provider know if your family members have HCM. Also, tell them about any family members with:

Heart failure
Atrial fibrillation — An irregular heartbeat that is often fast
Ventricular tachycardia — A fast heart rhythm that starts in the lower chambers of the heart
Ventricular fibrillation — A dangerous heart rhythm that can lead to SCD and needs emergency treatment
Stroke, heart attack, pacemaker placement, or heart transplant

Here are some other risk factors for HCM:

Unexplained syncope (fainting) — Passing out without a clear reason may mean a higher risk of sudden cardiac death.
Left ventricle thickness — A thicker left ventricle may mean a higher risk of sudden cardiac death.
Age — Most sudden cardiac deaths happen in people under the age of 35, but up to 20 percent of sudden deaths occur in people older than 65.
Abnormal blood pressure during exercise — A drop in blood pressure during exercise may raise the risk of sudden cardiac death, especially in people younger than 40.
Weak left ventricle — If this part of your heart doesn’t pump blood well, your risk may be higher. Your doctor can check this by measuring your left ventricular ejection fraction (LVEF) to see how much blood your heart pumps.

How Do Doctors Determine Risk?

Because hypertrophic cardiomyopathy is a genetic condition, knowing your family history of heart problems is important. This information helps doctors decide whether you should have genetic testing for HCM mutations.

This information, along with details about your symptoms — such as how often you have heart palpitations, fainting, shortness of breath during exercise, chest pain, or lightheadedness — can help guide testing and determine your risk of sudden cardiac death.

Your doctor may order tests to help determine your risk. These include:

Echocardiogram — This heart ultrasound shows how well your heart chambers work and measures heart thickness.
Electrocardiogram (EKG or ECG) — This test measures and charts the electrical activity of your heart and can catch irregular heartbeats as well as signs of thickening.
Holter monitor — Worn continuously at home, this device records your heart activity during your day-to-day activities.
Cardiac magnetic resonance imaging (MRI) — This test provides images of the heart and its valves and shows how well they work. Cardiac MRI can also show whether there is a large amount of fibrosis, or scar tissue, in the heart, which can raise the risk of SCD.
Stress test — This test, which involves walking or running on a treadmill, shows how well your heart performs during physical activity.
Cardiac CT scan — If an MRI is not an option, your healthcare provider may order a cardiac CT scan instead.

What Steps Can Be Taken To Reduce Risk?

If you’re diagnosed with HCM, your cardiologist will likely make some recommendations for how to manage your condition and reduce your risk of sudden cardiac arrest. These suggestions might include:

Consistent monitoring — Your cardiologist will monitor your heart for changes in size and thickness.

Medication use — While there aren’t any medications to prevent sudden cardiac death, your healthcare provider may prescribe medications to help treat some of your symptoms, like arrhythmias (irregular heartbeat).

Physical activity — Light exercise helps improve your heart function and can be helpful for those with HCM.

Manage long-term conditions — If you have long-term conditions like high blood pressure, sleep apnea, or obesity, your doctor may recommend medications or other interventions to help manage these conditions.

Consider an implantable cardioverter-defibrillator (ICD) — ICDs have helped reduce deaths from HCM to one-tenth of what they were before.

It’s important to discuss an ICD thoroughly with your healthcare provider to decide if it’s right for you, especially because it involves surgery. Some people feel anxious, depressed, or even have symptoms of post-traumatic stress disorder (PTSD) after getting an ICD.

If this happens to you, follow up with your cardiologist. Support and treatment can help.