Hypertrophic Cardiomyopathy

Hypertrophic cardiomyopathy is a heart condition where the muscle becomes abnormally thick, making it harder for the heart to pump blood properly. While many people live without symptoms, this genetic disease can lead to serious complications, including sudden cardiac death, particularly in young people and athletes.

Table of contents

• What Is Hypertrophic Cardiomyopathy?
• Types of Hypertrophic Cardiomyopathy
• Causes and Genetics
• Symptoms
• Possible Complications
• How Doctors Diagnose This Condition
• Treatment Options
• Lifestyle Changes and Self-Care
• Living With Hypertrophic Cardiomyopathy

What Is Hypertrophic Cardiomyopathy?

Hypertrophic cardiomyopathy (HCM) is a disease in which the heart muscle becomes thickened, also called hypertrophied^[1]. The term “hypertrophic” means something is bigger than it should be, while “cardiomyopathy” represents a group of conditions that affect the heart muscle^[4].

The thickening can affect any area of the heart’s muscle tissue, called the myocardium, but most commonly affects the septum, which is the middle wall that divides the heart into two sides^[4]. When the septum becomes thicker than usual, it can make the heart’s left lower chamber, called the left ventricle, have less space to pump blood^[1].

• Heart
• Left ventricle
• Interventricular septum
• Heart muscle (myocardium)
• Right ventricle
• Mitral valve

HCM affects about 1 in 500 people in the United States, making it a relatively common heart condition^[4]. However, many people don’t know they have it because they may have few or no symptoms^[1]. In the United States, HCM is the most common identifiable cause of sudden cardiac death in healthy people younger than 35, including well-trained athletes^[3].

Types of Hypertrophic Cardiomyopathy

There are two main types of hypertrophic cardiomyopathy, based on whether the thickened heart muscle blocks blood flow^[4]:

Obstructive HCM is the more common type, affecting about 2 in 3 people with HCM. In this type, the thickened part of the heart muscle is in the septal wall, which blocks or reduces blood flow from the left ventricle to the aorta, the main artery that carries blood to the rest of the body^[4]. This blockage is called left ventricular outflow tract obstruction^[3].

Nonobstructive HCM occurs when the heart muscle is thickened in other areas, such as the bottom of the heart, right ventricle, or entire left ventricle. In this type, the thickening doesn’t block blood flow out of the heart^[4].

In all cases of HCM, testing should be performed to detect outflow obstruction at rest or during physical activity to determine which type is present^[11].

Causes and Genetics

HCM is an autosomal dominant cardiac disease caused by mutations in genes that control the production of heart muscle proteins^[3]. This means that only one biological parent needs to have an altered gene to pass it on to their child. If someone in a family has been diagnosed with HCM, their child has a 50% (1 in 2) chance of having the condition^[5].

About 60% of patients with HCM have a known gene mutation, particularly in genes encoding elements of the sarcomere, which is the contractile machinery of the heart^[3]. Several hundred mutations in more than 27 genes have been associated with the HCM appearance^[11].

Gene changes cause about 3 in 5 cases of hypertrophic cardiomyopathy. Healthcare providers call this familial HCM^[4]. Because many different gene changes can cause HCM, the severity of the condition can vary widely, even within the same biological family. Some people who have the changed gene may never develop the disease^[4].

Up to 2 in 5 cases of HCM have no known cause. These cases don’t have a gene change that explains the condition, and researchers are currently studying other possible causes^[4].

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^[5]. However, most people with the condition receive a diagnosis around 40 years of age^[4]. Those who develop HCM before age 40 often have more symptoms and complications^[5].

Symptoms

Many people with hypertrophic cardiomyopathy don’t realize they have it because they have few, if any, symptoms^[1]. Some people with HCM do not have symptoms in the early stages but develop them over time^[5].

When symptoms do occur, they can include one or more of the following^[1][4]:

• Chest pain, especially during exercise
• Shortness of breath and fatigue, especially with physical activity
• Fainting, especially during or just after exercise or other physical activity
• Dizziness or feeling lightheaded
• Sensation of fast, fluttering, or pounding heartbeats, called palpitations
• Swelling in the ankles, feet, legs, stomach, or neck veins

You may have several of these symptoms or none at all. Symptoms may be worse when a person is dehydrated^[6]. If you have these symptoms, it’s crucial to see your healthcare provider^[4].

It’s important to get a prompt checkup to find the cause and receive the right care. You should see your healthcare professional if you have a family history of HCM or any symptoms related to hypertrophic cardiomyopathy^[1]. Call emergency services if you have rapid or irregular heartbeat or trouble breathing for more than a few minutes^[1].

Possible Complications

In a small number of people with HCM, the thickened heart muscle can cause serious complications^[1]. Most people with hypertrophic cardiomyopathy don’t experience complications, but because HCM can cause life-threatening health issues, it’s essential to see a cardiologist regularly if you have the condition^[4].

The characteristic cardiac structural changes in HCM can lead to^[3]:

• Dynamic left ventricular outflow obstruction
• Diastolic dysfunction, which means the heart has trouble relaxing and filling with blood
• Myocardial ischemia, where the heart muscle doesn’t get enough oxygen
• Arrhythmias, or irregular heartbeats
• Problems with how the body’s automatic nervous system controls the heart
• Mitral regurgitation, where blood leaks backward through the mitral valve

Specific complications of HCM can include^[4][5]:

• Atrial fibrillation, which can lead to blood clots and stroke
• Congestive heart failure
• Infective endocarditis, an infection of the heart lining
• Ventricular arrhythmias
• Sudden cardiac arrest and death

Sudden cardiac death is the most serious complication of HCM, particularly in young and asymptomatic patients^[11]. 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^[5].

How Doctors Diagnose This Condition

A healthcare professional will perform a physical exam and listen to your heart with a device called a stethoscope. A heart murmur may be heard while listening to the heart^[8]. The provider usually asks questions about your symptoms and your medical and family history^[8].

Obtaining a detailed family history is crucial to help in risk assessment for affected patients^[3]. When collecting your family health history to assess your risk for HCM, you should include information on family members who died suddenly, especially if they were younger than age 40, and information on family members with heart failure, atrial fibrillation, stroke, heart attack, or those who have had devices like pacemakers or defibrillators implanted^[5].

Tests are done to check the heart and look for causes of any symptoms. These may include^[8][7]:

Echocardiogram: An echocardiogram often is used to diagnose hypertrophic cardiomyopathy. Sound waves are used to create images of the beating heart. This test shows how well the heart’s chambers and valves are pumping blood and can see if the heart’s muscle is thicker than it should be^[8].

Electrocardiogram (ECG or EKG): This quick and painless test measures the electrical activity of the heart. Sticky patches called electrodes are placed on the chest and sometimes the arms and legs. An ECG can show irregular heartbeats and signs of heart thickening^[8].

Holter monitor: This small, portable ECG device records the heart’s activity. It’s worn for a day or two while you do your regular activities^[8]. A 24-hour Holter or longer-term monitor may be used to check heart rhythm^[7].

Cardiac MRI: This test uses powerful magnets and radio waves to create images of the heart. It provides information about the heart muscle and how the heart and heart valves work^[8].

Stress test: A stress test often involves walking on a treadmill or riding a stationary bike while the heart is monitored^[8].

Cardiac catheterization: In some cases, this procedure may be performed to get more detailed information about blood flow through the heart^[7].

Genetic testing is recommended for affected people and their family members^[6]. If someone in your family has been diagnosed with HCM, that person can have genetic testing to look for genetic changes that cause HCM. Once the genetic change is found in a person, other family members can have genetic testing for that change^[5].

Close family members of people who have been diagnosed with hypertrophic cardiomyopathy may be screened for the condition. This is most often done with an echocardiogram or with genetic testing^[7].

Treatment Options

Treatment depends on symptoms and other risk factors^[6]. The goals of treatment are to reduce symptoms, prevent complications, and reduce the risk of sudden cardiac death^[11]. A comprehensive patient history and thorough physical exam can help identify patients at risk of dangerous irregular heartbeats^[3].

Medications

If you have symptoms, you may need medicines to help the heart contract and relax correctly. These medicines may relieve chest pain or shortness of breath when exercising^[7]. Medications may include^[6][7]:

• Beta blockers are commonly used to help slow the heart rate and reduce the heart’s workload
• Calcium channel blockers, such as verapamil, can help the heart relax and fill with blood more effectively
• Disopyramide may be used in some cases to reduce outflow obstruction

A newer medication called mavacamten, a first-in-class inhibitor of cardiac myosin, has been approved for adults with symptomatic obstructive hypertrophic cardiomyopathy to improve exercise capacity and symptoms^[13].

Procedures and Devices

People with arrhythmias may need treatment such as medicines to treat the abnormal rhythm, blood thinners to reduce the risk of blood clots, or devices to control the heartbeat^[7].

Implantable cardiac defibrillator (ICD): An implanted defibrillator recognizes life-threatening heart rhythms and sends an electrical pulse to stop them. Sometimes a defibrillator is placed even if the patient has not had an arrhythmia but is at high risk for a deadly one^[7]. An ICD may be recommended in those with certain types of irregular heartbeat^[6].

Permanent pacemaker: This device may be implanted to control the heartbeat in some patients^[7].

Surgery

When blood flow out of the heart is severely blocked and symptoms become severe, surgical options may be considered^[7]:

Surgical myectomy: An operation called surgical myectomy involves removing part of the thickened heart muscle. People who have this procedure often show much improvement^[7]. Surgical myectomy is now a standard treatment for patients with drug-resistant disease^[11].

Alcohol septal ablation: In some cases, people may be given an injection of alcohol into the arteries that feed the thickened part of the heart. This procedure is also a standard treatment for appropriate patients^[11].

You may need surgery to repair the heart’s mitral valve if it is leaking^[7]. In rare cases, cardiac transplantation may be necessary for patients with severe symptoms that don’t respond to other treatments^[7].

Lifestyle Changes and Self-Care

Adopting certain lifestyle and dietary habits as part of your self-care routine is crucial to managing HCM^[16]. Patients can play a major role in their own treatment by living a healthy lifestyle, staying fit, and avoiding activities that can compromise their condition^[15].

Exercise and Physical Activity

Always follow your provider’s advice about exercise if you have hypertrophic cardiomyopathy. You may be told to avoid strenuous exercise^[7]. Most people with HCM could benefit from light to moderate intensity recreational activity, which refers to activities that target up to 70% of your maximum heart rate^[16].

Some light to moderate activities may include yoga, tai chi, walking, and golfing. Higher intensity exercises to consider limiting include running, swimming, or contact sports^[16]. It’s important to avoid intense burst of exercise, weightlifting, and competitive sports^[15]. You should not lift heavy objects while performing household chores^[15].

Get regular physical exercise at a level approved by your physician. Walking and biking in moderation can increase your endurance and contribute to your general sense of well-being^[15].

Daily Living

Important daily habits include^[15][18]:

• Stay hydrated: Keep drinking water throughout the day. Dehydration can worsen symptoms
• Follow a heart-healthy diet
• Watch your weight: Maintaining a healthy weight is important for heart health
• Avoid environmental extremes (heat/cold)
• Don’t smoke
• Avoid or limit alcohol use. Consult your physician before using alcohol
• Avoid hot tubs and saunas
• Don’t do street drugs. Cocaine and methamphetamines are extremely dangerous for HCM patients
• Don’t take diet pills or over-the-counter cold medications without checking with your doctor

General Health Management

• Pay strict attention to dental hygiene. A minor, untended gum infection can spread to the heart, leading to endocarditis^[15]
• Watch any cuts or scratches for signs of infection^[15]
• Learn how to manage stress through meditation, biofeedback, or relaxation exercises^[15]
• Keep a list of the medications you take, their dosages, how you take them, and how often^[15]
• Keep regular appointments with your cardiologist to monitor your condition^[15]

Living With Hypertrophic Cardiomyopathy

A near-normal life expectancy and a highly satisfactory quality of life are now realistic treatment goals for patients with HCM^[11]. The good news is that early diagnosis and treatment can help prevent complications^[4].

It’s a lifelong condition that can get worse over time, leading to serious complications^[4]. With treatment, the risk of death is less than 1% per year^[6]. Early intervention through pharmacologic means, implantable cardiac-defibrillator placement, and surgical intervention when warranted have greatly improved the survival rates of HCM in the last few decades^[3].

Because correct diagnosis and risk assessment can be life-saving, it’s important to update information regularly about your family health history and let your healthcare provider know about any new diagnoses, cardiac events, or sudden deaths in your family^[5]. Even if you don’t have a family health history of HCM, tell your healthcare provider if you develop any symptoms^[5].