Hypertrophic Cardiomyopathy - Cause, Symptoms, Management, and Prevention

Introduction:

Hypertrophic cardiomyopathy (HCM) is a condition in which the heart's left ventricle is affected. The left ventricle of the heart is the main chamber for pumping blood to other parts of the body. In this condition, the left ventricle walls get thickened and stiff. Because of this, the heart cannot pump sufficient blood to other parts of the body.

What Is Hypertrophic Cardiomyopathy?

Hypertrophic cardiomyopathy is a genetic defect. In this condition, abnormal genes affect the heart muscles. The muscles in the heart, especially the left ventricle, become stiff and thickened, resulting in reduced blood being taken in and out to other parts of the body with each heartbeat.

There are different types of HCM. These include,

• Obstructive HCM.

• Nonobstructive HCM.

Obstructive HCM (HOCM): This type is considered the most common. The wall (septum) between the left and right ventricles thickens in this type. This obstructs the blood flow from the left ventricle to the aorta (the body’s main artery).

Nonobstructive HCM: In this type, there is a thickening of the heart muscle but no obstruction to the blood flow and, hence, no blockage.

It is estimated that around 600,000 to 1.5 million people are affected by HCM in America. HCM is a complex heart disease that shows thickening of the heart muscle, the presence of stiffness in the left ventricle, mitral valve changes, and cellular changes.

It has been observed that younger people are more likely to be affected by HCM. The condition may be observed among all ages.

What Are the Causes of Hypertrophic Cardiomyopathy?

HCM is considered to be caused mainly by changes in the genes. A genetic mutation causes the heart muscle to thicken, resulting in HCM. The defective genes responsible for the growth of heart muscles cause HCM. This condition is hereditary, can be inherited from parents, and can be passed on to offspring.

Other causes include,

• High blood pressure.

• Aging.

• Sometimes, the cause of HCM has yet to be discovered.

What Are the Symptoms of Hypertrophic Cardiomyopathy?

The symptoms of HCM may be observed among a few individuals, and a few may not have any symptoms. Some may have symptoms only with exertion or exercise. A few may not exhibit symptoms in the initial stage but may exhibit them at a later stage.

The symptoms of HCM include,

• Chest pain may be observed during physical exertion.

• Shortness of breath can be seen with physical exertion.

• Weaknesses can be noticed.

• Arrhythmias (irregular heart rate) may be noticed.

• Lightheadedness or dizziness may be observed.

• Fainting or syncope may occur.

• Swelling may be observed in feet, ankles, legs, or abdomen.

• A fluttering or pounding feeling in the chest may be observed.

This condition is considered to be chronic and gets worse over time. This can cause poor functioning, long-term complications, financial and social burdens, and a decreased quality of life.

HCM may lead to other health conditions.

These include,

• Atrial fibrillation (arrhythmia that may cause blood clots).

• Heart failure.

• Stroke.

• Ventricular arrhythmias that may lead to cardiac arrest.

• Sudden cardiac arrest.

Although sudden cardiac arrest is considered rare, it may be seen among young individuals and competitive athletes in North America.

How to Diagnose Hypertrophic Cardiomyopathy?

The diagnosis of HCM can be done by

A physical examination and medical history are taken. Signs and symptoms are observed. The following tests are to be considered to diagnose HCM.

These include,

Cardiac MRI (Magnetic Resonance Imaging): This test provides images of the heart to find the thickening of the left ventricular wall.

Coronary Angiography: This test helps check the blood vessels for any blockages, if present.

Echocardiogram (ECHO): This test uses ultrasound waves to capture heart images. It helps detect the thickening of the heart muscle and the heart's pumping function.

Electrocardiogram (ECG): This test helps record the heart's electrical impulses. It can detect any abnormal rate or rhythm of the heart.

Electrophysiology Study: A thin tube is inserted into the heart through a blood vessel. This is done to measure the electrical activity.

Genetic Testing and Counseling: A blood test helps determine the genes responsible for HCM. After this, counseling is done to understand the process.

Holter Monitor: This device is worn throughout the day, and this helps measure the electrical activity throughout the day.

Stress Test: This test helps measure the heart's function while running or walking on a treadmill.

What Is the Treatment for Hypertrophic Cardiomyopathy?

The treatment of HCM depends on the presence of symptoms. Currently, there is only one medication available, which is disease-specific. Mavacamten, a medication approved by the FDA in April 2022, can treat obstructive HCM symptoms.

Individuals with HCM who do not show symptoms may be advised to follow a healthy lifestyle.

A healthy lifestyle includes,

• To stay active.

• Having a healthy diet.

• Maintaining a healthy weight.

• Practicing to have good quality sleep.

• Quitting smoking habits.

If an individual with HCM has other conditions like high blood pressure or diabetes, they should manage well to avoid heart complications.

Individuals with symptoms are managed through medications and procedures.

Medications: Medications used in HCM help improve function and symptoms. These may pose side effects, too.

Medications that help improve symptoms include,

• Beta-blockers.

• Calcium channel blockers.

• Diuretics.

Medications that help improve symptoms and function include,

• Myosin inhibitors.

Procedures: The procedures used to treat HCM include surgical and nonsurgical. These procedures include,

Septal Myectomy: This procedure is called septal reduction therapy or open heart surgery. This procedure is indicated when individuals do not respond well to medications alone and continue to have symptoms in the case of the obstructive type of HCM. The surgeon removes a part of the septum with a bulge in the wall, which can correct the blood flow within the heart and out to the body.

Alcohol Septal Ablation: This procedure is nonsurgical. It is also called nonsurgical septal reduction therapy. In this procedure, ethanol goes througha tube into the small artery, supplying blood to the thickened heart muscle due to HCM. Alcohol causes the death of cells. Because of this, the thickened tissue shrinks to its normal size. This procedure is indicated among older people as the risks and complications of heart surgery increase with age.

Cardiac Implantable Electronic Devices (CIEDs): Many devices can be implanted in the body to help the heart work better.

These include,

• Implantable Cardioverter Defibrillator (ICD): This device helps maintain a normal heartbeat. If an irregular heartbeat is detected, it sends an electric shock to the heart. This helps reduce the risk of sudden cardiac death.

• Pacemaker: This device uses electrical pulses to prompt the heart to beat normally. This device is used by those whose heart rate is slow.

• Cardiac Resynchronization Therapy (CRT) Device: This device helps coordinate contractions between the left and right ventricles.

Heart Transplant: This procedure is done among those affected by HCM who are at the end stage of the disease. A diseased heart is replaced with the heart of a donor.

What Is the Prognosis of Hypertrophic Cardiomyopathy?

The prognosis for HCM is good. Most individuals affected by HCM have a normal life expectancy without significant limitations or complications. A few individuals may pose a risk for complications like heart failure and sudden death.

How to Prevent Hypertrophic Cardiomyopathy?

There is no prevention for HCM. Hence, it becomes important to identify the disease as early as possible to take measures to treat HCM and avoid complications.

• Genetic testing may be done among those who have first-degree relatives with HCM.

• If this test is not done or is not helpful, repeated ECHO may be recommended if an individual has a family member with HCM.

• Adolescents and athletes should be screened for HCM every year.

• Athletes who compete may be screened once every five years.

How to Improve the Quality of Life With Hypertrophic Cardiomyopathy?

If an individual or a family member is affected by HCM, then certain changes are to be made to improve heart health.

These include,

• Limiting the intake of salt and fluid.

• Exercise should be done with care.

• Regular follow-ups are to be done to learn about the condition of the heart.

• Measures to be taken to reduce the risk of infections, especially infective endocarditis.

Conclusion:

Hypertrophic cardiomyopathy is a condition in which there is the presence of thickened heart muscle. This affects the blood flow and disrupts the functioning of the heart. Individuals affected by HCM may or may not show symptoms. Many of them lead a normal life, but HCM may cause serious complications. Hence, it becomes important to know about HCM, its causes, symptoms, management, and preventive aspects. Knowing about the condition helps identify the disease at the earliest. This, in turn, helps achieve effective treatment.