[HCM] Hypertrophic Cardiomyopathy

Overview and intro of Hypertrophic Cardiomyopathy (HCM)

Your heart is a muscle. Inside of it, there are four spaces, or chambers. If you have hypertrophic (hi-per-tro-fik) cardiomyopathy or HCM, your heart muscle gets thicker, making these chambers smaller. This may make it harder for your heart to pump blood out to your body.

If untreated or poorly managed, hypertrophic cardiomyopathy can cause other serious conditions such as heart failure, dangerous heart rhythms, and even sudden death. So finding it early is key.

HCM is usually passed down in families (inherited). If you or a family member has been diagnosed with HCM, be sure to talk with your clinician about genetic testing and screening.  

Also, it’s important to remember that you’re not alone. HCM is the most common genetic heart disease in the U.S. It affects at least 1 in 500 adults. But even more people may have it and not know they do.

As with any heart condition, it is important to take good care of yourself and follow your care team’s recommendations. Use this condition center to learn more about HCM.


In most cases, hypertrophic cardiomyopathy (HCM) is an inherited condition passed down in families. If you have HCM, you likely were born with a gene mutation that changes the “instruction manual” telling cells what to do. This change makes the heart muscle become too thick.

“Hypertrophy” means to thicken. This thickening can make it harder for the heart to relax and fill with blood and pump oxygen-rich blood to the body.  


HCM can be difficult to diagnose, especially as many people don’t have symptoms. When they do, it can be mistaken for other conditions, including heart valve disease—mitral valve disorders, aortic stenosis—exercise-induced asthma or anxiety.

Early diagnosis is important to avoid complications, including life-threatening heart rhythms and sudden death. Tragically, HCM is one of the most common reasons for sudden deaths among young people and athletes who didn’t know they had the condition.

HCM usually affects the main pumping chamber of the heart (left ventricle) and the muscle wall that separates the left and right sides of the heart (septum). If the muscle wall becomes thicker than normal, it can bulge into the lower chamber of the heart.

This bulge can disrupt the flow of blood to the main artery that carries blood to your body (aorta). If this happens, you may feel very tired or have a hard time catching your breath.

When do these changes happen? It varies. The thickening of the heart muscle often coincides with growth spurts in puberty as someone physically matures, and then it levels off. But many patients won’t notice anything. When they do, it might not be until middle age. Still, its presence can be deadly. A sudden death may be how it is found.

The good news is that with ongoing care, many people with HCM can live a long life. 

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