Hypertrophic Cardiomyopathy

1 What is Hypertrophic Cardiomyopathy?

Hypertrophic cardiomyopathy (HCM) is a disease of your heart muscles (myocardium) that cause them to become abnormally thickened. Due to the thickening, your heart has to work harder while pumping blood. Many people with this condition do not realize they have hypertrophic cardiomyopathy due to lack of noticeable symptoms. The symptoms, if present, are mild and do not cause significant problems. But few persons may experience chest pain, breathing problems or serious problems with heart rhythms (arrhythmias).

2 Symptoms

Signs and symptoms of hypertrophic cardiomyopathy, if present, include: 

  • Shallow and difficult breathing, especially during exercise
  • Pain in chest caused by physical exertion
  • Transient loss of consciousness, more frequently during or just after exercise 
  • Racing heartbeats (palpitations)
  • Abnormal heart sounds (Heart murmur) 

When to see a doctor?

See your doctor immediately if you experience symptoms such as shallow, rapid breathing and abnormal heartbeats (palpitations). Immediately call 911 or your local emergency number if any of the following symptoms last for more than a few minutes:

  • Rapid abnormal heartbeats
  • Breathing problems
  • Chest pain

3 Causes

Hypertrophic cardiomyopathy is caused by mutations in the gene that cause your heart muscles to thicken abnormally. In some cases, it can be caused by a condition called myofiber disarray in which heart muscle cells are arranged in abnormal patterns. Irregular heartbeats (arrhythmia) may result due to such abnormal arrangement. There are two forms of HCM, namely:

  • Obstructive hypertrophic cardiomyopathy: It is a more common form in which the wall (septum) separating two bottom chambers of the heart (ventricles) becomes thickened, resulting in reduced blood flow out of the heart.
  • Nonobstructive hypertrophic cardiomyopathy: In this form of HCM, your heart’s major pumping chamber (ventricle) becomes stiffened and cannot accommodate enough blood to allow sufficient blood flow out of the heart during a heartbeat. 

4 Making a Diagnosis

After reviewing your medical and family history and assessing signs and symptoms, your doctor can conduct a physical examination to diagnose hypertrophic cardiomyopathy. S/he may also you to go through various imaging tests such as:

  • Echocardiogram: It uses sound waves to create moving images of your heart which can help your doctor detect heart muscles, blood flow and movement of heart valves.
  • Electrocardiogram (ECG): It measures your heart’s electrical impulses. An abnormal ECG pattern could indicate enlarged heart chambers and abnormal heartbeats.
  • Treadmill stress test: This is the most common test for HCM. This test measures your heart rhythm, blood pressure and breathing while you walk on a treadmill. It helps to determine if your heartbeats become abnormal while exercising. 
  • Holter monitor: Your heart’s activity is continuously monitored over 24 hours or more with a wearable ECG device.
  • Cardiac MRI: Detailed images of your heart are created by using strong magnetic fields and radio waves. 
  • Cardiac catheterization: It involves inserting a catheter through a blood vessel, usually in your neck or groin area into your heart chambers. This test helps to determine obstructions in the blood flow through your heart. Rarely, a radioactive dye can be injected through the catheter to obtain images of your heart and blood vessels. 

Family screening

You may screen for HCM if any first-degree relative of yours has HCM. A genetic test can help you detect if you are carrying a faulty gene that may cause HCM. Discuss with your doctor or a genetic counselor to evaluate risks and benefit of genetic test.

5 Treatment

Treatment for hypertrophic cardiomyopathy aims to control symptoms and prevent sudden cardiac death in high-risk people.  Severity of the symptoms determine which particular treatment is appropriate. The treatment options include: 

  • Medication: A wide range of medications including beta blockers such as propranolol, atenolol or calcium channel blockers such as verapamil or diltiazem may be prescribed to slow heart rate and promote normal heart beats. For atrial fibrillation, you may need to take blood thinners such as warfarin, dabigatran or rivaroxaban. 
  • Surgery: Surgery is recommended to relieve symptoms that do not respond to medications.

     o Removing part of thickened septum: Also called septal myectomy, it involves surgical removal of a portion of a thickened septum, the wall that separates two ventricles. This surgery can improve blood flow and reduces backflow of blood through  the mitral valve (mitral regurgitation) 

     o Repairing the mitral valve: This surgery may be conducted during a septal myectomy.

  • Using alcohol to destroy thickened heart muscles: Also called septal ablation, it involves injecting alcohol through a catheter into the artery that supplies to the thickened tissues.
  • Implantable cardioverter-defibrillator (ICD): An ICD is a heartbeat-monitoring device used commonly in life-threatening arrhythmias such as ventricular tachycardia or ventricular fibrillation. The device is implanted just like a pacemaker. When you have life-threatening arrhythmia, the ICD gives off electrical shocks to bring your heart rhythm back to normal. 

6 Prevention

Being an inheritable disorder, hypertrophic cardiomyopathy is not preventable. However, an early detection can help better outcomes and reduced risks of complications.

How to prevent sudden death?

Implantable cardioverter-defibrillator (ICD) may be able to prevent sudden cardiac death, which affects approximately 1% of people with hypertrophic cardiomyopathy.

7 Lifestyle and Coping

Simple lifestyle modifications can be of immense value to help you reduce the risk of complications of hypertrophic cardiomyopathy. Here are some tips:

  • Stay active but limit high-intensity activities. Talk to your doctor before starting any exercise regimen.
  • Eat a heart-healthy diet. 
  • Maintain a healthy weight. 
  • Avoid heavy drinking. Talk to your doctor to know the safe level of drinking.
  • Follow your doctor’s directions while taking medications.
  • Visit your doctor regularly.

Diagnosis of HCM can leave you drenched in pain, fear and stress. Follow these tips to stay calm:

  • Manage stress with meditation, relaxation techniques or anything that you find comforting.
  • Stay close to your friends and family.
  • Live a healthy life. 

8 Risks and Complications

There are several risks and complications associated with hypertrophic cardiomyopathy.

Risks

Genetic link: HCM is an inheritable defect meaning you can develop the condition if your parents has this condition.

Complications

  • Arrhythmias: Abnormal or rapid heartbeat conditions such as atrial fibrillation, ventricular tachycardia and ventricular fibrillation may occur in a person with HCM. Blood clots that result due to atrial fibrillation may cause a stroke.
  • Reduced flow of blood leaving the heart can cause breathing problems during exertion, chest pain, dizziness and episodes of fainting.
  • Enlarged ventricle: In a few people, HCM can lead to a condition called dilated cardiomyopathy. 
  • Mitral valve problems: Increased force of blood flow through the mitral valve, the valve between your heart’s left atrium and left ventricle, can lead to backflow of blood to the left atrium. This is called mitral valve regurgitation
  • Heart failure: Heart failure can result when the heart muscles become so stiff that they cannot pump enough blood.
  • Sudden cardiac death: HCM increases your risk of sudden cardiac death. HCM-induced sudden cardiac death occurs most commonly before 30.
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