Learn About Hypertrophic Cardiomyopathy (HCM)

What is the definition of Hypertrophic Cardiomyopathy (HCM)?

Hypertrophic cardiomyopathy (HCM) is a condition in which the heart muscle becomes thick. Often, only one part of the heart is thicker than the other parts.

The thickening can make it harder for blood to leave the heart, forcing the heart to work harder to pump blood. It also can make it harder for the heart to relax and fill with blood.

Hypertrophic cardiomyopathy
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What are the alternative names for Hypertrophic Cardiomyopathy (HCM)?

Cardiomyopathy - hypertrophic (HCM); IHSS; Idiopathic hypertrophic subaortic stenosis; Asymmetric septal hypertrophy; ASH; HOCM; Hypertrophic obstructive cardiomyopathy

What are the causes of Hypertrophic Cardiomyopathy (HCM)?

Hypertrophic cardiomyopathy is most often passed down through families (inherited). It is thought to result from defects in the genes that control heart muscle growth.

Younger people are likely to have a more severe form of hypertrophic cardiomyopathy. However, the condition is seen in people of all ages.

What are the symptoms of Hypertrophic Cardiomyopathy (HCM)?

Some people with the condition may have no symptoms. They may first find out they have the problem during a routine medical exam.

In many young adults, the first symptom of hypertrophic cardiomyopathy is sudden collapse and possible death. This can be caused by highly abnormal heart rhythms (arrhythmias). It may also be due to a blockage that prevents the outflow of blood from the heart to the rest of the body.

Common symptoms include:

  • Chest pain
  • Dizziness
  • Fainting, especially during exercise
  • Fatigue
  • Lightheadedness, especially with or after activity or exercise
  • Sensation of feeling the heart beat fast or irregularly (palpitations)
  • Shortness of breath with activity or after lying down (or being asleep for a while)
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What are the current treatments for Hypertrophic Cardiomyopathy (HCM)?

Always follow your provider's advice about exercise if you have hypertrophic cardiomyopathy. You may be told to avoid strenuous exercise. Also, see your provider for regularly scheduled checkups.

If you have symptoms, you may need medicines such as beta-blockers and calcium channel blockers to help the heart contract and relax correctly. These drugs may relieve chest pain or shortness of breath when exercising.

People with arrhythmias may need treatment, such as:

  • Medicines to treat the abnormal rhythm.
  • Blood thinners to reduce the risk of blood clots (if the arrhythmia is due to atrial fibrillation).
  • A permanent pacemaker to control the heartbeat.
  • An implanted defibrillator that recognizes life-threatening heart rhythms and sends an electrical pulse to stop them. Sometimes a defibrillator is placed, even if the patient has not had an arrhythmia but is at high risk for a deadly arrhythmia (for example, if the heart muscle is very thick or weak, or the patient has a relative who has died suddenly).

When blood flow out of the heart is severely blocked, symptoms can become severe. An operation called surgical myectomy may be done. In some cases, people may be given an injection of alcohol into the arteries that feed the thickened part of the heart (alcohol septal ablation). People who have this procedure often show much improvement.

You may need surgery to repair the heart's mitral valve if it is leaking.

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What is the outlook (prognosis) for Hypertrophic Cardiomyopathy (HCM)?

Some people with hypertrophic cardiomyopathy may not have symptoms and will have normal lifespan. Others may get worse slowly or quickly. In some cases, the condition may develop into dilated cardiomyopathy.

People with hypertrophic cardiomyopathy are at higher risk for sudden death than people without the condition. Sudden death can occur at a young age.

There are different types of hypertrophic cardiomyopathy, which have different prognoses. The outlook may be better when the disease occurs in older people or when there is a particular pattern of thickness in the heart muscle.

Hypertrophic cardiomyopathy is a well-known cause of sudden death in athletes. Almost half of deaths due to this condition happen during or just after some type of physical activity.

When should I contact a medical professional for Hypertrophic Cardiomyopathy (HCM)?

Contact your provider if:

  • You have any symptoms of hypertrophic cardiomyopathy.
  • You develop chest pain, palpitations, faintness, or other new or unexplained symptoms.
Heart - section through the middle
Heart - front view
What are the latest Hypertrophic Cardiomyopathy (HCM) Clinical Trials?
Concomitant Hybrid Versus Catheter Ablation for Reinforcing Therapeutic Effect of Atrial Fibrillation With Hypertrophic Cardiomyopathy

Summary: The goal of this clinical trial is to compare the rhythm control effect in hypertrophic non-obstructive patients with non-paroxysmal atrial fibrillation by either concomitant catheter endocardial and thoracoscopic epicardial ablation or catheter ablation alone. The study aims to see if concomitant hybrid ablation can more effectively achieve rhythm control effect than catheter ablation alone in no...

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4D Flow Cardiac MRI Velocity Mapping in Patients With Hypertrophic Cardiomyopathy: Assessment of the Severity of the Left Ventricular Obstruction and Comparison With Echocardiography

Summary: Hypertrophic cardiomyopathy (HCM) is a frequent cardiac pathology with an estimated prevalence of 1/500 in France. The main risk factor for sudden death in this pathology is the presence and extent of left ventricular obstruction. To date, the only method allowing a reliable assessment of the extent of left ventricular obstruction is Doppler echocardiography. All patients with HCM should undergo c...

What are the Latest Advances for Hypertrophic Cardiomyopathy (HCM)?
Single coronary ostium with obstructive hypertrophic cardiomyopathy treated using the Morrow procedure: a case report.
Effective treatment of hypertrophic cardiomyopathy with left ventricular outflow tract obstruction using a covered stent.
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Donohue syndrome and use of continuous subcutaneous IGF1 pump therapy.
Who are the sources who wrote this article ?

Published Date: May 08, 2022
Published By: Michael A. Chen, MD, PhD, Associate Professor of Medicine, Division of Cardiology, Harborview Medical Center, University of Washington Medical School, Seattle, WA. Also reviewed by David C. Dugdale, MD, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.

What are the references for this article ?

Ho CY, Ommen SR. Hypertrophic cardiomyopathy. In: Libby P, Bonow RO, Mann DL, Tomaselli GF, Bhatt DL, Solomon SD, eds. Braunwald's Heart Disease: A Textbook of Cardiovascular Medicine. 12th ed. Philadelphia, PA: Elsevier; 2022:chap 54.

McKenna WJ, Elliott PM. Diseases of the myocardium and endocardium. In: Goldman L, Schafer AI, eds. Goldman-Cecil Medicine. 26th ed. Philadelphia, PA: Elsevier; 2020:chap 54.

What are some Advocacy Organizations?

Simon’s Heart is a nonprofit organization dedicated to raising awareness about, and preventing deaths from, conditions that cause sudden cardiac arrest in children.