Hypertrophic cardiomyopathy (HCM) is a genetic heart disorder characterized by the thickening of the heart muscle, primarily affecting the left ventricle—the chamber responsible for pumping oxygenated blood to the rest of the body. HCM is considered one of the most common inherited cardiac disorders, affecting people of all ages and ethnic backgrounds. The severity of symptoms and the age at which they appear can vary widely among individuals, ranging from mild or no symptoms to severe impairment of heart function.
Types of Hypertrophic Cardiomyopathy
- Asymmetric Septal Hypertrophy (ASH): This is the most common type of HCM, where the thickening mainly occurs in the wall (septum) dividing the two ventricles. The thickened septum can obstruct blood flow from the left ventricle to the aorta, leading to a condition called left ventricular outflow tract obstruction (LVOT obstruction).
- Apical Hypertrophic Cardiomyopathy: In this form of HCM, the thickening primarily affects the apex (tip) of the left ventricle. It is most commonly observed in individuals of Japanese descent. Apical HCM may cause chest pain, shortness of breath, and an increased risk of arrhythmias.
- Concentric Hypertrophic Cardiomyopathy: This type is characterized by uniform thickening of the entire left ventricle, rather than localized thickening in specific areas. It is less common than asymmetric septal hypertrophy and often associated with a worse prognosis.
- Mid-Ventricular Hypertrophic Cardiomyopathy: This type involves thickening of the middle portion of the left ventricle, between the apex and the base. It is a rare subtype of HCM and can present with symptoms similar to other types.
It’s worth noting that some individuals may have a combination of these patterns, or the distribution of the hypertrophy may change over time.
Common HCM Symptoms
- Chest pain or discomfort
- Breathing difficulties, particularly during vigorous activity or exertion
- Fatigue or tiredness
- Palpitations (rapid or irregular heartbeat)
- Fainting or near-fainting episodes
- Dizziness or lightheadedness
- Heart murmurs (abnormal heart sounds)
- Swelling of the ankles, feet, or legs (edema)
- Arrhythmias (abnormal heart rhythms)
- Sudden cardiac arrest (rare but can occur)
What Could Possibly Cause HCM?
Hypertrophic cardiomyopathy (HCM) is primarily caused by genetic mutations that affect the proteins responsible for regulating the growth and contraction of heart muscle cells. These mutations are typically inherited, meaning they are passed down from parents to their children. However, in some cases, HCM can occur due to spontaneous mutations that are not inherited.
The specific genes associated with HCM include:
- MYH7: Mutations in the MYH7 gene, which provides instructions for a protein called beta-myosin heavy chain, are the most common cause of HCM. These mutations lead to the overgrowth of heart muscle cells.
- MYBPC3: Mutations in the MYBPC3 gene, which encodes the cardiac myosin-binding protein C, are also common cause of HCM. These mutations disrupt the normal structure and function of the heart muscle.
- TNNT2, TNNI3, and TPM1: Mutations in genes such as TNNT2 (troponin T), TNNI3 (troponin I), and TPM1 (alpha-tropomyosin) can also contribute to the development of HCM.
Not all individuals with these genetic mutations will develop HCM, and the severity of the condition can vary widely. Other factors, such as modifier genes and environmental factors, may influence the expression and progression of the disease.
Diagnosis of HCM
- Medical history and physical examination: The healthcare provider will review your medical history, and family history of heart disease, and ask about your symptoms. They will also perform a thorough physical examination, including listening to your heart with a stethoscope.
- Electrocardiogram (ECG): An ECG measures the electrical activity of the heart and can detect abnormal heart rhythms or patterns associated with HCM.
- Echocardiogram: This non-invasive imaging test uses sound waves to produce images of the heart. It helps assess the thickness of the heart muscle, the movement of the heart walls, and the function of the heart valves.
Suitable Treatment Options for HCM
- Medications: Medications are commonly prescribed to manage symptoms and improve heart function. Beta-blockers and calcium channel blockers can help relax the heart muscle, reduce heart rate, and control blood pressure. Other medications, such as anti-arrhythmic or anticoagulants, may be used to manage abnormal heart rhythms or prevent blood clots.
- Septal myectomy or alcohol septal ablation: In cases where the thickened heart muscle obstructs blood flow, surgical procedures like septal myectomy (removal of part of the thickened muscle) or alcohol septal ablation (injection of alcohol to selectively damage a portion of the thickened muscle) may be considered to relieve the obstruction.
- Implantable cardioverter-defibrillator (ICD): People at high risk of life-threatening arrhythmias may require an ICD. This device is implanted under the skin and can deliver an electric shock to restore normal heart rhythm in case of a dangerous arrhythmia.
- Genetic counseling: Since HCM is a genetic disorder, individuals diagnosed with HCM and their family members may benefit from genetic counseling to understand the inheritance pattern and the risk of passing the condition to future generations.
Priority Questions To Ask Your Doctor
- What is hypertrophic cardiomyopathy (HCM), and how does it affect my heart?
- What caused my HCM? Is it genetic?
- What are the symptoms of HCM? How can I recognize them?
- Do I need to make any lifestyle changes? What can I do to manage my condition?
- What medications are commonly prescribed for HCM? What are their potential side effects?
- Are there any restrictions on physical activities or exercises I should follow?
- Should I be concerned about sudden cardiac arrest or other potential complications?
- What tests or further evaluations are necessary to understand the severity of my condition?
- Are there any specific dietary considerations I should be aware of?
- Will I need regular monitoring or follow-up appointments? How often should I see a cardiologist?