Am I at Risk for Sudden Cardiac Death From Hypertrophic Cardiomyopathy (HCM)?

One of the most frightening things about hypertrophic cardiomyopathy (HCM) is that it raises one’s risk for sudden cardiac death (SCD). If you or a loved one are affected by this rare genetic heart condition, it’s normal to have concerns about your risk and what you may be able to do to protect your health.

Fortunately, SCD is rare, and treatment advances have made it even rarer. “While it’s a real concern, it’s relatively uncommon, especially with modern monitoring and treatment,” says Diala Steitieh, MD, the director of the hypertrophic cardiomyopathy program at Weill Cornell Medicine in New York City.

• A history of cardiac arrest or ventricular tachycardia
• A first-degree relative with HCM who had SCD
• Age 35 or younger
• Fainting (syncope)
• Low blood pressure during or after exercise
• Left ventricle thickness of 30 millimeters or more
• Non-sustained ventricular tachycardia (NSVT), which occurs when a person has three or more consecutive ventricular beats with a pulse of more than 100 beats per minute for 30 seconds or less

Unexpectedly, the severity of your HCM doesn’t predict your SCD risk. “Symptoms like shortness of breath or chest discomfort may affect quality of life, but don’t mean a higher risk of sudden death,” says Steitieh.

Other traditional heart health risk factors such as obesity or a sedentary lifestyle don’t influence SCD risk either, says Victor Farah, MD, the clinical lead of the hypertrophic cardiomyopathy program at Allegheny Health Network in Pittsburgh.

Your cardiologist will look at your heart rhythm, cardiac imaging test results, family history, and clinical symptoms to assess your SCD risk. In some cases, they may use a risk calculator like the American Heart Association’s Sudden Cardiac Death Risk Calculator, which calculates how likely it is that a person with HCM will experience SCD within the next five years.

Regardless of whether they opt to use a risk calculator, your cardiologist should assess your SCD risk when you’re first diagnosed with HCM and each year thereafter, says Dr. Farah.

While these calculators are easy to find online, resist the urge to use them at home. “These tools are designed to be used by clinicians who can interpret the results in the proper context,” says Steitieh. “Although patients may come across these calculators online, using them without medical guidance can be misleading, as not all risk factors are captured by a single score.”

With that said, ICDs may not be best for everyone, as they come with some drawbacks like an increased risk of infection. Talk with your cardiologist about whether an ICD may be right for you.

Being proactive about your HCM care matters, too. “Staying engaged in regular cardiology follow-up appointments, taking prescribed medications, and avoiding dehydration are all important,” says Steitieh.

In many cases, when SCD occurs in a young athlete, their HCM was undetected. “If it’s a 15-year-old who died on the football field, most of the time we didn’t know he had a heart condition,” says Matthew Martinez, MD, the director of Atlantic Health System Sports Cardiology at Morristown Medical Center in Morristown, New Jersey. “People who are diagnosed and treated can return to [their] sport and do really well.”

“Most people with HCM live full, active lives and never experience this complication,” says Steitieh.

Still, it’s normal to feel concerned about SCD if you have HCM. If you’re feeling anxious about your risk, talk with your cardiologist.

“I often emphasize that we now have excellent tools to identify those at higher risk and to intervene early when needed,” says Steitieh. “Education, open communication, and individualized care are key to helping patients feel informed and reassured.”

• Hypertrophic cardiomyopathy (HCM) thickens heart walls and can disrupt the heart's electrical system, leading to dangerous arrhythmias. But sudden cardiac death (SCD) remains rare, affecting only about 1 percent of patients annually.
• Cardiologists assess SCD risk using factors like family history, fainting spells, and specific heart measurements rather than general symptoms like shortness of breath.
• The most effective tool for preventing SCD is an implantable cardioverter-defibrillator (ICD), which has led to a 10-fold decrease in SCD among people with HCM since the early 2000s by automatically correcting irregular heart rhythms.
• While SCD is a notable concern for young athletes, research shows it’s just as likely to occur during rest as during exercise, and most people with HCM can lead full, active lives with proper medical monitoring.