Treatment Strategies for Hypertrophic Cardiomyopathy

Introduction:

Hypertrophic cardiomyopathy (HCM) is the most common inherited cardiac disorder in the United States. Based on echocardiographic studies, the condition affects one in 500 individuals. The thickening of the heart muscle often characterizes HCM. Over time, it reduces the ability of the heart to pump blood or take in enough blood to meet the body's demands, resulting in heart failure, stroke, cardiac arrhythmias, and sudden cardiac death. HCM is often treated by a cardiologist or pediatric cardiologist. Diagnosis is usually based on one's medical history, family history, physical examination, and some diagnostic tests. This article mainly focuses on treatment strategies for hypertrophic cardiomyopathy.

What Is Hypertrophic Cardiomyopathy?

Hypertrophic cardiomyopathy (HCM) is a condition that causes the thickening of the muscles of the left lower chamber of the heart (left ventricle), the main pumping chamber of the heart. The walls of the left ventricle get thick and stiff. With time, the heart becomes unable to pump or take in enough blood during each heartbeat to meet the demands of the body. HCM can lead to serious health issues like atrial fibrillation (arrhythmia that can cause blood clots), heart failure, stroke, and sudden cardiac death. Hypertrophic cardiomyopathy most often runs in families (inherited). It is believed to be caused by defects in the genes that regulate the growth of the heart muscle.

What Are the Types of Hypertrophic Cardiomyopathy?

HCM is divided into two subtypes:

• Obstructive: The most prevalent type, hypertrophic obstructive cardiomyopathy (HOCM), is characterized by a thickening of the septum, or wall, that separates the left and right ventricles. This may prevent or hinder blood flow from the left ventricle to the body's main artery, the aorta.

• Non-obstructive: In non-obstructive HCM (HNCM), the heart muscles are thickened but do not obstruct blood flow.

What Are the Symptoms of Hypertrophic Cardiomyopathy?

The signs and symptoms of HCM can vary from individual to individual. Some individuals do not experience any symptoms at all, but others may experience some symptoms that include:

• Arrhythmia (irregular heart rate or rhythm).

• Chest pain.

• Fatigue.

• Fluttering or pounding feeling in the chest.

• Heart murmur.

• Lightheadedness.

• Dizziness.

• Fainting.

• Shortness of breath.

• Swelling in legs, feet, and ankles.

With time, symptoms tend to get worse, eventually lowering one's ability to perform day-to-day activities.

What Are the Treatment Strategies for Hypertrophic Cardiomyopathy?

Early treatment is essential for hypertrophic cardiomyopathy to prevent the complications associated with it. There are various treatment strategies that manage symptoms and reduce the risk of complications in such individuals, as follows:

1. General Measures:

• Exercise: Individuals diagnosed with hypertrophic cardiomyopathy should engage in moderate-intensity physical activities. High-intensity physical activities like athletics, high-performance sports, or competitive sports should be avoided.

• Avoid Noxious Substances: Noxious substances such as nicotine or alcohol should not be taken by individuals with HOCM (hypertrophic obstructive cardiomyopathy). If one takes alcohol, it can exacerbate outflow tract obstruction (restriction of blood flow from the heart) and can cause abnormal heartbeat (arrhythmias).

• Antibiotic Prophylaxis: Antibiotic prophylaxis is recommended in patients with HOCM to prevent infective endocarditis.

2. Implantable Cardioverter Defibrillator(ICD): Some patients with a high risk of sudden cardiac death (SCD) need to implant an ICD. It is quite challenging to assess individuals with a high risk of SCD in HCM patients. For this reason, five major risk factors have been identified to determine who needs an ICD.

• Family History: Any close family member with sudden cardiac death caused by HCM before the age of 45.

• Non-sustained Ventricular Tachycardia (NSVT): It is a type of arrhythmia (abnormal heart rhythm) and is a sensitive marker for increased risk of sudden cardiac death.

• Syncope (Fainting): Syncope at rest or during exercise is considered an important risk marker for SCD for all age groups.

• Abnormal Blood Pressure Response During Exercise: During exercise, there is a mild increase in systolic blood pressure, which is almost less than 20 mmHg. Abnormal blood pressure response during exercise is marked as a progressive fall in blood pressure during exercise or a fall in the systolic pressure by 20 mmHg after an initial increase, especially in younger patients.

• Extreme Left Ventricular Hypertrophy: Extreme left ventricular hypertrophy with wall thicknesses exceeding 30 mm is associated with the risk of SCD.

3. Treatment of Asymptomatic Patients: HCM patients with no symptoms are usually treated with beta-blockers based on pathophysiological considerations.

4. Treatment of Symptomatic Patients With HNCM:

• Heart rate control in individuals with HNCM (hypertrophic non-obstructive cardiomyopathy) is done using beta blockers or Verapamil-type calcium antagonists.

• In patients with hypertension or HNCM exhibiting congestion symptoms, diuretics, ACE (angiotensin-converting enzymes) inhibitors, and AT (angiotensin) receptor antagonists may be prescribed.

• HNCM individuals with atrial fibrillations are often associated with a risk of cardiac embolic events. Such cases require prompt administration of anticoagulants. Also, Amiodarone can be used to prevent the recurrence of atrial fibrillations but not the risk of sudden cardiac death.

5. Treatment of Symptomatic Patients With HOCM:

• Medication: Beta-blockers to improve left ventricular filling. If beta blockers are not effective, verapamil-type calcium antagonists can be given as an alternative.

• Septal Myectomy: Septal myectomy is a standard therapy for patients with HOCM who cannot be treated with pharmacotherapy. The procedure involves removing or thinning the part of the thickened septum to reduce the gradient causing obstruction.

• Percutaneous Septal Ablation: Percutaneous septal ablation involves injecting ethanol into one of the septal branches supplying the hypertrophied myocardium (thickening of cardiac muscles), leading to a thinning of the septum over the long term. This procedure results in the reduction or elimination of the obstruction in the majority of cases.

Conclusion:

Hypertrophic cardiomyopathy (HCM) is a common genetic condition causing abnormal thickening of heart muscles, most commonly affecting the right ventricle, which interferes with the pumping action of the heart muscle. This condition can result in various health issues. Treatment of HCM may differ depending on the presence and absence of symptoms and type of HCM. The outlook for those with this condition has greatly improved due to developments in medical technology and surgical procedures. Early detection and intervention are essential to provide the optimal care and quality of life for individuals affected by HCM.