About Hypertrophic Cardiomyopathy (HCM)

What it is

Hypertrophic cardiomyopathy is a common genetic disorder that affects about 1 in 500 people1 and causes the heart muscle to become thicker and stiff.23 This makes it harder for the heart to work properly because

• The thickened heart muscle can obstruct blood flow out of the heart.
• The heart requires more energy and oxygen to work, especially during exercise.
• The heart can hold less blood, so the amount of blood pumped to the rest of the body with each heartbeat is decreased.

Complications

People with HCM can develop complications such as heart failure, atrial fibrillation, ventricular tachycardia, and ventricular fibrillation.2 HCM can lead to sudden death, especially in children, teens, young adults, and competitive athletes, who may have no or few symptoms and not know they have a heart problem.24

HCM can develop at any point in a person’s life. Most people with HCM are born with what appears to be a normal heart and develop HCM later. Those who develop HCM before age 40 often have more symptoms and complications.5

People at risk

HCM sometimes runs in families. In such cases, a child of an affected parent has a 50% (1 in 2) chance of having HCM.6 Other family members also have an increased chance of having HCM. Importantly, the age at which other family members develop HCM can vary within families.

When collecting your family health history to assess your risk for HCM

• Include information on family members who died suddenly, especially if they were younger than age 40.
• Include information on family members with heart failure, atrial fibrillation, ventricular tachycardia, ventricular fibrillation, stroke, heart attack, heart transplant, implantable cardioverter-defibrillator (ICD), or pacemaker.
• Update information regularly, and let your healthcare provider know about any new diagnoses, cardiac events, or sudden deaths in your family.

Causes

HCM is caused by changes in genes that control the production of heart muscle proteins.6 You only need a change in one copy of the gene to develop HCM.

Testing and diagnosis

Genetic testing

If someone in your family has been diagnosed with HCM, that person can have genetic testing to look for genetic changes that cause HCM. Testing in your family should start with someone who has HCM. In cases in which a young person died suddenly, genetic testing might have been done as part of the autopsy.

Once the genetic change that causes HCM is found in a person, other family members can have genetic testing for that change. If genetic testing does not find a genetic change that causes HCM in the affected family member, they should follow up with their cardiologist (heart healthcare provider) on a regular basis. Sometimes genetic testing finds a genetic change that is not known to cause HCM at the time, but future studies show that it causes HCM. Also, further genetic testing might be recommended to include any newly identified genetic changes that cause HCM that were not included in earlier testing.

Diagnosis

If genetic testing shows that you have the genetic change for HCM, you will need to see a cardiologist to check your heart for signs of HCM. If the genetic change that causes HCM in your family is not known, parents, siblings, and children of the person with HCM will need to be checked for signs of HCM. Cardiologists can diagnose HCM using

• Echocardiogram (Echo), which is non-invasive and uses sound waves to take pictures of your heart
• Cardiac magnetic resonance imaging (MRI), which is a non-invasive way to get detailed images of your heart

Know the symptoms

Knowing the symptoms of HCM is important if you have a family health history of HCM, especially if you have the genetic change for HCM that runs in your family. Even if you don’t have a family health history of HCM, tell your healthcare provider if you have any of the following common symptoms of HCM:

• Feeling tired or lacking energy
• Shortness of breath, especially with physical activity
• Chest pain, especially with physical activity
• Fainting or feeling dizzy or lightheaded
• Swelling in the ankles, feet, legs, or stomach

Some people with HCM do not have symptoms in the early stages but develop them over time. Thus, even if you do not currently have signs or symptoms of HCM, you might need repeated monitoring based on your age and other factors if you have a family health history of HCM, especially if you have the genetic change for HCM that runs in your family.7 Let your healthcare provider know right away if you develop any of the symptoms of HCM.

What you can do

If you or your child has HCM, the healthcare provider may recommend

• Regular monitoring: Adults need to see a cardiologist (heart healthcare provider) every 3-5 years to look for changes in the heart using echocardiogram, electrocardiogram (ECG), and checking for symptoms of HCM. For children and teens, the interval is every 1-3 years.6
• Medication: Currently, no medicines have been proven to prevent HCM or lower the chances of dying. However, a variety of medicines can be used to treat symptoms of HCM. New drugs are currently being tested in clinical trials that may help patients with HCM.
• Light to moderate physical activity: Light to moderate physical activity has been shown to help those with HCM. Those engaging in very high intensity activities such as competitive sports should discuss their risk with an HCM-trained specialist.
• Surgery: Your healthcare provider might recommend surgery if you have severe HCM.
• Controlling other chronic conditions: High blood pressure, sleep apnea, and being overweight or having obesity can increase your risk of developing complications of HCM. Making lifestyle changes and taking other steps to manage these conditions are important for people with HCM.

While these steps cannot prevent HCM, they can help keep your heart as healthy as possible and decrease your likelihood of developing complications.