Hypertrophic cardiomyopathy (HCM) is a disease in which the heart muscle becomes abnormally thick (hypertrophied). The thickened heart muscle can make it harder for the heart to pump blood.

Hypertrophic cardiomyopathy often goes undiagnosed because many people with the disease have few, if any, symptoms and can lead normal lives with no significant problems. However, in a small number of people with HCM, the thickened heart muscle can cause shortness of breath, chest pain or problems in the heart's electrical system, resulting in life-threatening abnormal heart rhythms (arrhythmias) or sudden death.

Signs and symptoms of hypertrophic cardiomyopathy may include one or more of the following:

• Chest pain, especially during exercise
• Fainting, especially during or just after exercise or exertion
• Heart murmur, which a doctor might detect while listening to your heart
• Sensation of rapid, fluttering or pounding heartbeats (palpitations)
• Shortness of breath, especially during exercise

When to see a doctor

A number of conditions can cause shortness of breath and heart palpitations. It's important to get a prompt, accurate diagnosis and appropriate care. See your doctor if you have a family history of HCM or any symptoms associated with hypertrophic cardiomyopathy.

Call 911 or your local emergency number if you have any of the following symptoms for more than a few minutes:

• Rapid or irregular heartbeat
• Difficulty breathing
• Chest pain

Hypertrophic cardiomyopathy is usually caused by abnormal genes (gene mutations) that cause the heart muscle to grow abnormally thick.

In most people with hypertrophic cardiomyopathy, the muscular wall (septum) between the two bottom chambers of the heart (ventricles) becomes thicker than normal. As a result, the thicker wall may block blood flow out of the heart. This is called obstructive hypertrophic cardiomyopathy.

If there's no significant blocking of blood flow, the condition is called nonobstructive hypertrophic cardiomyopathy. However, the heart's main pumping chamber (left ventricle) may become stiff. This makes it hard for the heart to relax and reduces the amount of blood the ventricle can hold and send to the body with each heartbeat.

People with hypertrophic cardiomyopathy also have an abnormal arrangement of heart muscle cells (myofiber disarray). This can trigger arrhythmias in some people.

Hypertrophic cardiomyopathy is usually passed down through families (inherited).

If you have a parent with hypertrophic cardiomyopathy, you have a 50% chance of having the genetic mutation for the disease.

Parents, children or siblings of a person with hypertrophic cardiomyopathy should ask their doctors about screening for the disease.

Many people with hypertrophic cardiomyopathy (HCM) don't have significant health problems. But complications of hypertrophic cardiomyopathy can include:

• Atrial fibrillation. Thickened heart muscle, as well as the abnormal structure of heart cells, can cause changes in the heart's electrical system, resulting in fast or irregular heartbeats. Atrial fibrillation can also increase your risk of developing blood clots, which can travel to your brain and cause a stroke.
• Blocked blood flow. In many people, the thickened heart muscle blocks the blood flow leaving the heart, causing shortness of breath with exertion, chest pain, dizziness and fainting spells.
• Mitral valve problems. If the thickened heart muscle blocks the blood flow leaving the heart, the valve between the left atrium and left ventricle (mitral valve) may not close properly. As a result, blood can leak backward into the left atrium (mitral valve regurgitation), possibly leading to worsening symptoms.
• Dilated cardiomyopathy. In a very small number of people with HCM, the thickened heart muscle may become weak and ineffective. The ventricle becomes enlarged (dilated), and its pumping ability becomes less forceful.
• Heart failure. The thickened heart muscle can eventually become too stiff to effectively fill the heart with blood. As a result, your heart can't pump enough blood to meet your body's needs.
• Sudden cardiac death. Rarely, hypertrophic cardiomyopathy can cause heart-related sudden death in people of all ages. Because many people with hypertrophic cardiomyopathy don't realize they have it, sudden cardiac death may be the first sign of a problem. It can happen in seemingly healthy young people, including high school athletes and other young, active adults.

There is no known prevention for hypertrophic cardiomyopathy. But it's important to identify the condition as early as possible to guide treatment and prevent complications.

If you have a first-degree relative — a parent, sibling or child — with hypertrophic cardiomyopathy, doctors may recommend genetic testing to screen for the condition. However, not everyone with HCM has a currently detectable mutation. Also, some insurance companies may not cover genetic testing.

If genetic testing isn't done, or if the results aren't helpful, then your doctor may recommend echocardiograms on a regular basis if you have a family member with hypertrophic cardiomyopathy. Adolescents and competitive athletes should be screened once a year. Adults who don't compete in athletics should be screened every five years.

Your doctor will examine you and ask questions about your signs, symptoms, and medical and family history.

Tests

Your doctor will likely order tests to diagnose hypertrophic cardiomyopathy (HCM) or rule out other conditions that can cause similar symptoms.

• Echocardiogram. An echocardiogram is commonly used to diagnose hypertrophic cardiomyopathy. This test uses sound waves (ultrasound) to see if your heart's muscle is abnormally thick. It also shows how well your heart's chambers and valves are pumping blood.

  Sometimes, an echocardiogram is done while you exercise, usually on a treadmill. This is called an exercise stress test. Treadmill stress tests are commonly used to diagnose people with hypertrophic cardiomyopathy.

• Electrocardiogram (ECG or EKG). Sensors (electrodes) attached to adhesive pads are placed on your chest and sometimes legs. They measure electrical signals from your heart. An ECG can show abnormal heart rhythms and signs of heart thickening. In some cases, a portable ECG, called a Holter monitor, is needed. This device records your heart's activity continuously over one to two days.
• Cardiac MRI. A cardiac MRI uses powerful magnets and radio waves to create images of your heart. It gives your doctor information about your heart muscle and shows how your heart and heart valves work. This test is often done with an echocardiogram.

The goal of hypertrophic cardiomyopathy treatment is to relieve symptoms and prevent sudden cardiac death in people at high risk. Your specific treatment depends on the severity of your symptoms. Together, you and your doctor will discuss the most appropriate treatment for your condition.

Medications

Medications can help reduce how strong the heart muscle squeezes and slow the heart rate so that the heart can pump blood better. Medications to treat hypertrophic cardiomyopathy and its symptoms may include:

• Beta blockers such as metoprolol (Lopressor, Toprol-XL), propranolol (Inderal, Innopran XL) or atenolol (Tenormin)
• Calcium channel blockers such as verapamil (Verelan, Calan SR,) or diltiazem (Cardizem, Tiazac)
• Heart rhythm drugs such as amiodarone (Pacerone) or disopyramide (Norpace)
• Blood thinners such as warfarin (Coumadin, Jantoven), dabigatran (Pradaxa), rivaroxaban (Xarelto) or apixaban (Eliquis) to prevent blood clots if you have atrial fibrillation

Surgeries or other procedures

Several different surgeries or procedures are available to treat cardiomyopathy or its symptoms. They range from open-heart surgery to implantation of a device to control your heart rhythm.

• Septal myectomy. This open-heart surgery may be recommended if medications do not improve your symptoms. It involves removing part of the thickened, overgrown wall (septum) between the heart chambers. Septal myectomy helps improve blood flow out of the heart and reduces backward flow of blood through the mitral valve (mitral regurgitation).

  The surgery may be done using different approaches, depending on the location of the thickened heart muscle. In one type, called apical myectomy, surgeons remove thickened heart muscle from near the tip of the heart. Sometimes the mitral valve is repaired at the same time.

• Septal ablation. This procedure destroys the thickened heart muscle with alcohol. The alcohol is injected through a long, thin tube (catheter) into the artery supplying blood to that area. Possible complications include disruption of the heart's electrical system (heart block), which requires implantation of a pacemaker.
• Implantable cardioverter-defibrillator (ICD). An ICD is a small device that continuously monitors your heartbeat. It's implanted in your chest like a pacemaker. If a life-threatening arrhythmia occurs, the ICD delivers precisely calibrated electrical shocks to restore a normal heart rhythm. ICD has been shown to help prevent sudden cardiac death, which occurs in a small number of people with hypertrophic cardiomyopathy.

Lifestyle changes can reduce your risk of complications related to hypertrophic cardiomyopathy. Your doctor may recommend lifestyle changes, including:

• Using caution when playing sports. Competitive sports are generally not recommended for people with hypertrophic cardiomyopathy, with the possible exception of some low-intensity sports. You may be able to participate in low- to moderate-intensity exercise as part of a healthy lifestyle. Discuss specific recommendations with your doctor.
• Eating a healthy diet. A healthy diet is an important part of maintaining your heart health.
• Maintaining a healthy weight. Maintaining a healthy weight will prevent excessive stress on your heart and reduce health risks associated with surgery or other procedures.
• Reducing alcohol use. If you have symptoms or a history of rhythms provoked by alcohol, ask your doctor for guidance about safe levels of alcohol use. Drinking too much alcohol can trigger irregular heart rhythms and can lead to increased blockage of blood flow in your heart.
• Taking your medications. Make sure to take your medications as prescribed.
• Having regular medical appointments. Your doctor may recommend regular follow-up appointments to evaluate your condition. Let your doctor know if you have any new or worse symptoms.

Pregnancy

Women who have hypertrophic cardiomyopathy can generally have normal pregnancies. However, if you have hypertrophic cardiomyopathy, your doctor may recommend that you see a doctor experienced in caring for women with high-risk conditions during your pregnancy.

Being diagnosed with hypertrophic cardiomyopathy can cause a range of difficult emotions. Like many people with this condition, you may experience feelings of grief, fear and anger. These responses are appropriate to the lifestyle changes that come with your diagnosis.

To cope with your condition:

• Reduce your stress. Find ways to reduce your stress.
• Get support. Get support from your friends and family.
• Follow lifestyle changes your doctor recommends. Making healthy lifestyle changes, such as eating a healthy diet and maintaining a healthy weight, can help you cope with living with your condition.

You may be referred to a doctor trained in diagnosing and treating heart conditions (cardiologist). Here's some information to help you prepare for your appointment.

What you can do

• Find out if you need to follow any pre-appointment restrictions, such as changing your activity level or your diet.
• Write down your symptoms and how long you've had them.
• Take a list of all your medications, vitamins or supplements.
• Write down your key medical information, including other diagnosed conditions.
• Write down key personal information, including any recent changes or stressors in your life.
• Write down questions to ask your doctor.

Questions to ask your doctor

• What's the most likely cause of my symptoms?
• What kinds of tests do I need?
• What treatments can help?
• What risks does my heart condition create?
• How often will I need follow-up appointments?
• Do I need to restrict my activities?
• Should my children or other first-degree relatives be screened for this condition, and should I meet with a genetic counselor?
• How will other conditions that I have or medications I take affect my heart problem?

In addition to the questions that you've prepared to ask your doctor, don't hesitate to ask questions during your appointment.

What to expect from your doctor

Your doctor is likely to ask you a number of questions. Being ready to answer them may make time to go over points you want to spend more time on. You may be asked:

• When did you begin experiencing symptoms, and how severe are they?
• Have your symptoms changed over time? If so, how?
• Does exercise or physical exertion make your symptoms worse?
• Have you ever fainted?
• Do you have a family history of heart disease?

What you can do in the meantime

Before your appointment, ask your family members if any relatives have been diagnosed with hypertrophic cardiomyopathy or have experienced unexplained, sudden death. It will help your doctor to know as many details as possible about your family medical history.

If exercise makes your symptoms worse, avoid strenuous exercise until you have seen your doctor and received specific exercise recommendations.