by Kohnle D
(Cardiomyopathy, Hypertrophic—Adult; HCM—Adult; Idiopathic Hypertrophic Subaortic Stenosis—Adult; Asymmetric Septal Hypertrophy—Adult; ASH—Adult; HOCM—Adult; Hypertrophic Obstructive Cardiomyopathy—Adult)


Hypertrophic cardiomyopathy (HCM) is a form of cardiomyopathy. The heart muscle thickens more than it should because of problems with the genes. The thick muscle can cause several probelms such as:

  • Making it harder for the heart to work. It causes strain on the rest of the heart.
  • Interrupting flow of blood out of the heart.
  • Put pressure on nearby heart valve, called mitral valve. This can make the valve leaky.
  • Change the rhythm of the heart. It can make the heart pump in a disorganized way. Can cause abnormal rhythms but this is rare.

There are 2 types of hypertrophic cardiomyopathy:

  • Hypertrophic obstructive cardiomyopathy (HOCM)—the muscle between the 2 valves of the heart becomes so enlarged that it obstructs the blood flow in the heart
  • Nonobstructive hypertrophic cardiomyopathy—the muscle is not large enough to block blood flow.
Normal Heart and Heart With Hypertrophic Cardiomyopathy
Hypertrophic Cardiomyopathy
Copyright © Nucleus Medical Media, Inc.


Causes of HCM include:

  • A gene that causes the abnormal structure of the heart muscle. It can be inherited or can happen from changes in the genes over time.
  • A defective gene that controls growth of the heart muscle
  • Infection

In people over age 60, HCM is likely to be caused by or related to high blood pressure.

Risk Factors

HCM is usually most severe when it occurs in younger people, but it can occur at any age.

Other factors that may increase your chances of HCM include:

  • Having a family member with HCM
  • Being over age 60 and having hypertension


Symptoms include:

  • Chest pain
  • Fainting, particularly during exercise
  • Lightheadedness, particularly following exercise
  • Rapid heartbeat
  • Shortness of breath or difficulty breathing
  • General fatigue
  • Tiring easily during exercise or activity
  • Shortness of breath when lying down

These symptoms can be caused by some of the side effects of the condition, including heart arrhythmias. The blocked or reduced blood flow is usually the cause of symptoms like lightheadedness, fainting, and difficulty breathing.


The doctor will ask about symptoms and past health. A physical exam will be done.

A blood test may be done to look for changes or possible causes. Amyloidosis, sarcoidosis, coronary artery disease, or valvular heart disease can cause a different type of cardiomyopathy.

A stress test may also be done to see how the heart works under pressure. Images of the heart may be taken with:

Electrical activity of the heart may need to be tracked. This can be done with an ECG that can be worn all day.


Many people with HCM live a normal, healthy life with few symptoms. However, HCM does increase the risk of sudden death.

Treatment focuses on managing symptoms and preventing problems. Treatment may include:


Medicines may be used to help the heart work better. These may include:

  • Beta-blockers and calcium channel blockers
  • Antiarrhythmics
  • Blood thinners


Surgery may be needed to remove thickened part of the heart muscle. It may be done if the muscle is blocking too much blood flow from the heart.

Surgery may also be done to repair or replace the mitral valve if it is leaking.

Alcohol Septal Ablation

Alcohol is injected into the blood vessels that feed the enlarged heart. It will make part of the tissue shrink back. This should decrease blockage in the heart and improve blood flow out of the heart.

Implantable Cardioverter Defibrillators (ICD)

An ICD can help to control abnormal heart rhythms. It send an electrical impulse automatically when needed. It may be done if there is an increased risk for sudden death.


Some chronic heart issues or medical conditions increase the risk of HCM. Following the care plan may help to decrease the risk of HCM developing.


American Heart Association 

Cardiomyopathy Association 


Canadian Cardiovascular Society 

Heart and Stroke Foundation of Canada 


Cardiomyopathy in adults. American Heart Association website. Available at: Accessed September 15, 2020.

Explore cardiomyopathy. National Heart, Lung, and Blood Institute website. Available at: Accessed September 15, 2020.

Hypertrophic cardiomyopathy. EBSCO DynaMed website. Available at: . Accessed September 15, 2020.

What is HCM? St. Luke's Roosevelt Hospital Center website. Available at: Accessed September 15, 2020.

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