Hypertrophic Cardiomyopathy

Hypertrophic cardiomyopathy (HCM) is the most common genetic cardiac condition, occurring in at least one out of every 500 adults. HCM causes the walls of the heart to thicken, which affects the ability of the heart to effectively pump blood flow to the rest of the body. This also causes the heart muscle to become stiff, and does not allow the heart to relax normally.

What causes hypertrophic cardiomyopathy?

HCM is often caused by a change (or "mutation") in one of many genes that are responsible for helping coordinate the contraction and relaxation of the heart muscle. Although we have two copies of each gene, a mutation in one copy causes the gene not to work correctly and is enough to cause HCM.

A person with a mutation has a 50 percent chance of passing on the mutation to each of their children. That means that in families with HCM, usually around 50 percent of members are affected. Family members with HCM may experience different symptoms and complications of HCM.

What symptoms does hypertrophic cardiomyopathy cause?

Many people with hypertrophic cardiomyopathy do not experience symptoms, which is why it often takes a long time to diagnose this condition. When symptoms do occur, the most common are:

Trouble breathing
Chest pain
Fatigue
Decreased ability to do daily activities
Lightheadedness/dizziness
Fainting
Rapid or irregular heartbeat

Even if you don’t have symptoms, you should see a doctor if you have a close family member with HCM.

How is hypertrophic cardiomyopathy diagnosed?

A diagnosis of hypertrophic cardiomyopathy involves a full evaluation, including

Medical history
Family history
Physical exam
Electrocardiogram (ECG) and other cardiac testing

The most common imaging test used to diagnose HCM is an echocardiogram, or ultrasound of the heart, which measures the size of your heart and its ability to pump blood.

More advanced imaging, such as a cardiac magnetic resonance (CMR), may be done to help your doctors better see the heart muscle and to determine the amount of scar tissue in your heart. You may also have other tests, such as heart rhythm monitor, genetic testing, and exercise stress testing.

What are complications of hypertrophic cardiomyopathy?

Complications of HCM can vary and can include:

Reduced or blocked blood flow
Fainting or passing out
Mitral valve disease
Abnormal heart rhythms, such as atrial fibrillation and ventricular tachycardia
Heart failure, which can cause you to retain fluid
In rare cases, sudden death

I have a history of family member who has hypertrophic cardiomyopathy. What are the next steps should I take?

At-risk family members should see a cardiologist for a screening electrocardiogram and echocardiogram.

If the person with hypertrophic cardiomyopathy has a genetic mutation that can be identified, at-risk relatives can have genetic testing. Your results can help you and your doctor decided how often you should get screening or follow-up.

Genetic Testing in Hypertrophic Cardiomyopathy

Genetic testing can help us differentiate HCM from other cardiac diseases (especially “HCM mimics,” which also increase heart muscle wall thickness) and make a definitive diagnosis. Testing will also help your doctor figure out the best way to treat and manage your condition.

With genetic testing, we can identify which family members of a person with HCM are at risk of developing the condition themselves. This helps guide how we care for these at-risk relatives.

Along with our highly specialized team of medical geneticist and genetic counselors, we will work with you to get a detailed, three-generation family history and offer genetic testing as part of our comprehensive evaluation. After testing, we will make sure to explain what your results mean for you and your family.