Hypertrophic Cardiomyopathy

Hypertrophic cardiomyopathy (HCM) is a genetic form of heart disease that thickens areas of your heart muscle. It most often affects the wall dividing your lower heart chambers. A thicker wall means there’s less open space inside your heart’s main pumping chamber (left ventricle). This may limit how much blood your left ventricle holds and sends to your body. HCM affects anywhere from 1 in 200 to 1 in 500 people around the world. Many people are undiagnosed.

HCM is a lifelong condition that can get worse over time. In some people, it never leads to symptoms or issues. Others have symptoms that disrupt their life. The most severe cases can cause your heart to suddenly and unexpectedly stop beating. Hypertrophic cardiomyopathy is the most common cause of sudden cardiac death in athletes under age 35.

That may sound scary. But there’s good news. With medications or procedures to treat HCM, you can often live as long as those who don’t have HCM. And you can feel better from day to day. The key is learning if you’re at risk — for example, if HCM runs in your family. Getting a diagnosis early lets a healthcare provider monitor and treat the condition over time.

Types of hypertrophic cardiomyopathy

There are two main types:

• Obstructive HCM: Your heart muscle is too thick in the area leading up to your aortic valve, which sends blood out of your heart. The thick muscle forms an “obstruction” that may limit how much blood can leave your heart.
• Nonobstructive HCM: There isn’t an obstruction near your aortic valve. But other areas of your heart muscle may be too thick or stiff. This can lead to blood flow issues.

The obstructive form is more common. It generally causes more severe or disruptive symptoms earlier in life.

Symptoms of hypertrophic cardiomyopathy

HCM symptoms tend to come and go based on what you’re doing at the time. You’re more likely to have symptoms if you’re dehydrated, stressed, drinking alcohol, eating heavy meals or exerting yourself.

Common HCM symptoms include:

• Shortness of breath, especially with physical activity (most common symptom)
• Fatigue
• Heart palpitations
• Dizziness
• Fainting
• Chest pain or discomfort

If you have any of these symptoms, it’s crucial to see a healthcare provider.

Signs of HCM

Some people have no symptoms and only find out they have HCM when certain signs show up on imaging tests. These include:

• Thickened areas of your heart muscle: An area that’s at least 15 millimeters (mm) thick may mean you have HCM, particularly if healthcare providers haven’t identified another reason for you to have a thick heart muscle. The threshold is 13 mm in young children.
• Left ventricular outflow tract obstruction (LVOTO): This means something is getting in the way of blood leaving your heart. It might be the thick muscle itself or the nearby mitral valve. Part of this valve may get pulled toward the thick heart wall and block blood flow.

Hypertrophic cardiomyopathy causes

Most cases of HCM are genetic and run in families. That means you inherit certain gene changes that can cause the condition to develop. HCM follows an autosomal dominant inheritance pattern. So, if you have an HCM gene, there’s a 50% chance that your biological child will inherit it.

The severity of HCM can vary widely, even within the same family. Just because you inherit the gene doesn’t mean you’ll develop the disease. Some people are carriers. This means they have the altered gene but never develop symptoms or complications. Others start to have symptoms at some point in life — often during the teen years or young adulthood.

Healthcare providers can find a gene change in some people who have HCM. It often affects the MYBPC3 or MYH7 genes, but there are also other responsible genes, including ones that scientists haven’t found yet.

Complications of this condition

Most people with HCM don’t experience complications, especially if they receive treatment. But it’s possible for HCM to cause serious or life-threatening issues, including:

• Atrial fibrillation, which can lead to blood clots or a stroke
• Congestive heart failure
• Infective endocarditis
• Mitral regurgitation
• Ventricular arrhythmias
• Cardiac arrest, which can be fatal

How doctors diagnose this condition

Healthcare providers diagnose hypertrophic cardiomyopathy based on a medical history, physical exam and testing. Your provider will review your health records and ask about your symptoms. They’ll also want to know if anyone in your family has a history of HCM, other heart diseases or sudden death. They’ll listen to your heart and lungs with a stethoscope. If you have HCM, they may hear a heart murmur.

Tests you may need include:

• Echocardiogram (echo): This is the main test that diagnoses HCM. It can reveal if certain areas of your heart muscle are too thick. It also shows blood flow through your heart. An echo helps distinguish between different types of HCM.
• Exercise stress echo: This test can show how your heart responds to exertion. It’s especially useful if a resting echo doesn’t show signs of obstruction, but you have symptoms when you exert yourself.
• Electrocardiogram (EKG/ECG): This records your heart’s electrical activity and usually shows abnormal results with HCM. It can also check for dangerous heart rhythms.
• Holter or patch monitor: These devices record your heart’s electrical activity for longer than an EKG.
• Cardiac MRI: This imaging test can give your provider another look at your heart to fill in any gaps from the echo. It also helps your provider learn more about your risk for sudden cardiac death.
• Gene testing: This blood test can find gene changes linked with HCM.

HCM screenings

HCM screenings are routine tests for people at risk due to family history. It’s important to get screenings if you have a biological parent, sibling or child with the condition.

If you learn about a family member’s diagnosis, tell your healthcare provider. They’ll explain the screening schedule you should follow. Typically, this involves having an echo test and an EKG every few years.

If you have an HCM diagnosis, tell your family. They’ll need to talk to their healthcare providers about getting screened. Healthcare providers are especially concerned with first-degree relatives, including biological parents, siblings and children.

How is hypertrophic cardiomyopathy treated?

Together, you and your heart doctor (cardiologist) will decide on a treatment plan based on how HCM is affecting you and your risk for serious issues, like ventricular arrhythmias and cardiac arrest, both of which can be fatal. The goal of treatment is to reduce symptoms and lower the risk of complications. Your treatment plan may include monitoring, medications and/or procedures.

Monitoring

This means you go in for routine check-ups and tests, like echo tests and EKGs. Monitoring might be all you need for many years. That’s often the case if your risk for complications is low and you don’t have symptoms.

If you’re receiving treatments, like medications, your doctor will also keep a close eye on your condition. You’ll have tests every so often to check your heart function and assess your risk level. These tests allow your doctor to adjust your treatments as needed.

Medications

The medications your doctor prescribes for you depend on the type of HCM you have. The U.S. Food and Drug Administration (FDA) recently approved medications called cardiac myosin inhibitors to treat obstructive HCM. These medications, which target the root cause of the disease, include:

• Mavacamten (Camzyos™)
• Aficamten (Myqorzo™)

Researchers haven’t found targeted treatments for nonobstructive HCM yet. Although there are clinical trials looking at possible medications, the main treatments that your doctor may prescribe to help your heart work better and reduce symptoms include:

• Beta-blockers
• Calcium channel blockers 
• Diuretics (in certain cases where heart failure develops)

For either form of HCM, you may need medications to manage heart disease risk factors or abnormal heart rhythms.

Procedures

You may need surgery or a less invasive procedure to manage symptoms or lower your risk of cardiac arrest. Options include:

• Septal myectomy: A surgeon removes a small amount of the thickened heart muscle. This widens the path your blood takes from your left ventricle to your aorta. This is an open-heart surgery. It’s only for people with obstructive HCM.
• Alcohol septal ablation: A healthcare provider injects isopropyl alcohol into an artery that supplies blood to the area of thickened heart muscle. This shrinks the tissue to improve blood flow. This is a less invasive procedure for those who can’t have a septal myectomy.
• Implantable cardioverter defibrillator (ICD) placement: A cardiologist places a small device in your chest called an ICD. The device constantly monitors your heart. It shocks your heart back to a normal rhythm if a dangerous heart rhythm occurs.

When should I see my healthcare provider?

You’ll need to see your cardiologist regularly so they can check on your heart. They’ll let you know how often to come in for follow-up visits based on the condition’s severity and your treatment plan.

If possible, it’s best to receive care through a hospital system that’s experienced in treating hypertrophic cardiomyopathy.

What can I expect if I have this condition?

HCM is a lifelong condition. Your outlook depends on how severely the condition affects blood flow and whether you develop symptoms or complications. Some people inherit HCM but stay free of symptoms their whole lives. Others develop issues at a young age. Seeing your cardiologist regularly and following your treatment plan can help protect your heart and overall health.

Your cardiologist will guide you on things like:

• Exercise: In general, doctors recommend light or moderate intensity exercise for people with HCM. Always check with your cardiologist before starting a new exercise routine.
• Medications to avoid: When you’re living with HCM, there are some medicines and supplements that aren’t safe for you to take.
• Self-care: There are things you can do from day to day that help you have fewer symptoms. For example, limiting alcohol and staying hydrated are key measures to take.

Life expectancy

In the past, hypertrophic cardiomyopathy often shortened a person’s life expectancy. But advances in treatment have changed that. Today, with treatment, HCM usually doesn’t affect how long a person lives. Your cardiologist can give you the most accurate sense of what to expect in your case.