HCM is a genetic disease that you can inherit from a parent. It occurs when a gene experiences a mutation — or change — in a way that makes the gene work differently than it should.
In many people with HCM, the disease is autosomal dominant. This means it only takes one copy of a gene mutation to inherit the disease. You get a copy of each gene from each parent. So, having one parent with the disease means each child has a 50% chance of inheriting the gene and disease.
Several genes and many mutations can cause HCM. Other genetic and environmental factors can also affect the disease. Because of this, the disease can look different in each person it affects.
It’s also possible to inherit a gene mutation in a way other than an autosomal dominant inheritance. When this happens, a person can be a gene carrier without having the disease.
Symptoms and potential testing options
Some people with HCM don’t have symptoms. Others may have mild symptoms, or their symptoms may happen when they’re physically active.
Often, the first HCM symptom is shortness of breath. Other symptoms can include:
- atypical heart rhythms
- chest pain
- dizziness
- fainting
- fatigue
- lightheadedness
- swelling in the feet or ankles
In rare cases, HCM can cause sudden cardiac death as the first symptom of the condition. This is when the heart stops beating suddenly. Sudden cardiac death may often happen to people of younger ages.
When symptoms occur, doctors can use information from a physical exam and testing to make a diagnosis. Testing usually involves heart tests, including:
- echocardiogram, which is an imaging exam to see how your heart looks and works
- MRI, which is a detailed imaging exam of the heart
- electrocardiogram, which is a test to measure your heart’s rate and rhythm
- Holter monitoring or event monitoring to record your heart’s activity for 24 hours or longer
- stress test to see whether your heart can tolerate increased work
Family history is also important for testing and diagnosis. If someone in your family has HCM, genetic testing can help other family members.
Genetic testing starts with the person who has HCM. Once testing helps find a gene mutation, that person’s parents, siblings, and children can get testing. It’s important to work with a genetic counselor for these tests. They can help you understand the tests and their limitations.
People without symptoms may not need medical treatment for HCM. Instead, doctors may recommend eating a heart-healthy diet, getting regular physical activity, and trying other lifestyle changes. Treatment options for people with symptoms depend on the disease’s type and severity.
Many HCM medications can only improve the symptoms and prevent complications. They don’t target your heart function. Examples include:
- antiarrhythmics to regulate heart rate
- beta-blockers and calcium channel blockers to reduce the heart’s workload
- blood thinners to prevent blood clots
- diuretics to remove extra fluid
Also, the Food and Drug Administration (FDA) approved medication that can help target the underlying cause of HCM and improve symptoms and function. Its name is mavacamten (Camzyos).
Surgeries and procedures may also help treat HCM, including:
- implantable devices, such as a pacemaker or a cardioverter defibrillator
- septal ablation, which is a catheter-based procedure that shrinks thickened heart muscle areas
- septal myectomy, which is open heart surgery to remove thickened heart muscle areas to improve blood flow through the heart
- heart transplant, which may help people with advanced disease
The medical field has made great advances in recognizing and treating HCM. For many people with the condition, the outlook is good. They can have a typical life expectancy and manage the disease with early diagnosis.