About Hypertrophic Cardiomyopathy

Overview

Hypertrophic cardiomyopathy (HCM) is a heart condition characterized by the thickening (hypertrophy) of the heart muscle. It is a form of inherited cardiomyopathy where the heart muscle becomes thicker than usual, particularly in the left ventricle. HCM can occur in individuals with a family history of the condition (familial HCM) or without any family history (nonfamilial HCM). In familial HCM, the thickening usually occurs in the interventricular septum, which is the muscular wall separating the left and right ventricles of the heart. This thickening can obstruct blood flow and lead to symptoms such as abnormal heart sounds (heart murmurs) and other signs of the condition. However, some individuals with HCM may not have physical obstruction but experience less efficient pumping of blood. Symptoms can vary among affected individuals, and some may not have any symptoms at all.

Causes and Risk Factors

Hypertrophic cardiomyopathy (HCM) is characterized by certain root causes and risk factors that can be categorized into non-modifiable and modifiable factors.

Root causes of HCM:

• Cardiomyocyte hypertrophy: Enlargement of heart muscle cells
• Interstitial fibrosis: Increased connective tissue between heart muscle cells
• Disorder of cardiomyocyte fiber arrangement: Abnormal organization of heart muscle fibers

Non-modifiable risk factors of HCM cannot be changed or controlled. These include:

• Family history of HCM: Having a close relative with HCM increases the risk.
• Genetic mutations: Certain genes, such as MYH7 and MYBPC3, are associated with HCM.

Modifiable risk factors of HCM can be influenced or changed. These include:

• Unhealthy diet: A diet high in salt and low in potassium may increase the risk.
• Lack of physical activity: Sedentary lifestyle can contribute to HCM.
• Obesity: Being overweight or obese is a modifiable risk factor for HCM.
• High stress levels: Chronic stress may impact heart health.
• Excessive alcohol consumption: Heavy drinking can increase the risk.
• Tobacco use: Smoking or using tobacco products can contribute to HCM.

It's important to note that while these modifiable risk factors can be addressed, it's always best to consult with a healthcare professional for personalized advice.

Symptoms

HCM can have different symptoms depending on the severity and extent of heart muscle thickening. Here are the most common early symptoms of HCM:

• Dizziness: Reduced blood flow or irregular heart rate from HCM may cause dizziness, especially when standing up suddenly after resting.
• Fainting: Dizziness from HCM can lead to fainting in some cases.
• Fatigue: HCM can cause excessive tiredness, even after getting enough rest or sleep.
• Shortness of breath: This symptom may worsen after physical activity.
• Chest pain: Blood flow and irregular heart rate can cause chest pain, which may worsen after eating a large meal or exercising.

As HCM progresses or becomes more severe, additional symptoms may occur:

• Edema: Swelling in the stomach or extremities can be a sign of HCM.
• Gastrointestinal problems: Symptoms like diarrhea, vomiting, and loss of appetite may occur, especially in infants and young children.

It's important to note that symptoms can vary from person to person, and some individuals may not experience any symptoms at all. If you suspect you have HCM or are experiencing any concerning symptoms, it's crucial to consult with a healthcare professional for an accurate diagnosis and appropriate management.

Diagnosis

To diagnose HCM the following examinations, tests, and procedures are commonly performed:

• Medical history review: Your healthcare provider will gather information about your personal and family medical history.
• Physical exam: The healthcare provider will look for physical signs of HCM, such as a heart murmur, irregular heartbeats, signs of heart failure (like leg swelling or shortness of breath), and abnormal blood pressure responses.
• Lab tests: Blood draws and other laboratory tests may be ordered to check for specific markers or rule out other conditions that could be related to HCM.
• Imaging studies: These may include X-rays, MRI (magnetic resonance imaging) scans, or echocardiograms (ultrasound of the heart) to visualize the structure and function of the heart.
• Clinical procedures: Based on your symptoms, additional tests or specialized procedures, such as a cardiac catheterization, may be recommended.

To determine the severity of HCM, additional examinations, tests, and procedures that may be performed include:

• Electrocardiography (ECG or EKG): This test records the electrical activity of the heart to assess abnormalities in heart rhythm and structure.
• Holter monitoring: A portable device is used to record your heart's activity over a 24-hour period to detect any irregularities.
• Stress tests: These evaluate how your heart responds to physical exertion and can help assess its function under stress.
• Genetic blood tests: These tests can identify specific genetic mutations associated with HCM in some cases.
• Cardiac catheterization: This invasive procedure involves inserting a thin tube into a blood vessel to measure pressures within the heart chambers and perform further assessments.

It's important to note that these are general descriptions, and specific recommendations should be discussed with your healthcare provider.

Treatment Options

The goals of treatment for HCM are to manage symptoms, reduce the risk of complications, and improve overall quality of life. Here are the different types of treatments and how they work to achieve these goals:

• Medications:
  • Beta-blockers: Help reduce blood pressure and normalize heart rhythm
  • Calcium channel blockers: Lower blood pressure and can also help with heart rhythm
  • Cardiac myosin inhibitors: Improve heart contractions
  • Diuretics: Reduce fluid accumulation and associated swelling
• Therapies:
  • Cardiac device implants (e.g., pacemakers): Regulate heart rate
  • Septal reduction therapy: Decrease the size of thickened heart tissues
  • Open-heart surgery: Recommended for significant obstruction in the lower heart chamber
  • Alcohol septal ablation: Involves injecting alcohol into a heart muscle artery to shrink thick tissue
• Health behavior changes:
  • Lifestyle modifications: Maintain a healthy weight, exercise regularly, quit smoking, and limit alcohol intake
• Emerging treatments:
  • Gene editing, RNA-based therapies, and targeted small molecules: Under investigation for their potential to change the underlying causes of HCM at a molecular level
  • Cardiac myosin modulators (e.g., mavacamten): Show promise in reducing blockage in the heart’s main pumping pathway and improving symptoms.

It's important to note that treatment plans should be tailored to individual patients. Consult with your healthcare professional for personalized advice.

Medication dosing may be affected by many factors. Check with your health care professional about dosing for your individual situation.Side effects can occur. Check with your health care professional or read the information provided with your medication for side effect information.