Cardiovascular Diseases



Hypertrophic Cardiomyopathy


Hypertrophic cardiomyopathy (HCM) is a disease of the structure of the heart cells. The heart muscle becomes hypertrophied (thick) and its cells develop an abnormal structure. This is a genetic disease that is caused by a genetic mutation. The children of someone with hypertrophic cardiomyopathy have a 50% chance of carrying the mutation associated with HCM and therefore of developing the condition. The disease can develop at any age but does so particularly in adolescence and at the start of adulthood. For every 1000 people, 1 to 2 are born with this genetic abnormality and most are asymptomatic.

There are many forms of hypertrophic cardiomyopathy: the heart muscle may be affected symmetrically or, more often, asymmetrically (certain walls of the heart are more often affected than others). Also, the hypertrophied (thickened) muscle can cause a blockage in the heart, which is known as hypertrophic cardiomyopathy with obstruction.

hypertrophic cardiomyopathy is the main cause of sudden death in young people under the age of 40.

Causes and/or risk factors 

There are no risk factors for hypertrophic cardiomyopathy aside from having a genetic predisposition, meaning being a carrier of the mutation. However, people with hypertrophic cardiomyopathy are more at risk of sudden death if:

  • They have arrhythmia (ventricular tachycardia)
  • They have previously experienced an episode of unexplained fainting
  • The hypertrophy (thickness) of the heart muscle is very severe (> 30 mm)
  • Close relatives died suddenly at a young age (before the age of 50 to 60)

Since the risk of sudden death increases during intense physical activity, hypertrophic cardiomyopathy patients must avoid all types of competitive sports.


The majority of hypertrophic cardiomyopathy patients have a benign form of the disease and are therefore asymptomatic. However, someone with hypertrophic cardiomyopathy can experience:

  1. Shortness of breath upon exertion
  2. Angina (chest pain) upon exertion or at rest
  3. Palpitations, which may be associated with arrhythmia
  4. Dizziness or even fainting (syncope)
  5. Edema (swelling) in the legs

After filling out a comprehensive questionnaire and performing a physical exam, the doctor will prescribe some of the following tests if he or she suspects cardiomyopathy:

Hypertrophic cardiomyopathy has a genetic cause, and a genetic mutation can be identified in approximately 50% of patients with this condition. The doctor may then recommend a consultation at the Genetics Centre, where staff will conduct:

  • Molecular genetic testing of a blood sample
  • A family assessment

Family members are also screened with an ECG and echocardiography to ensure that they do not show clinical signs of the disease.


There is currently no method or treatment to prevent the onset or development of hypertrophic cardiomyopathy.


Hypertrophic cardiomyopathy treatment consists of first using medication to relieve the symptoms caused by the obstructed blood flow (when the thickened heart muscle causes a blockage in the opening of the left ventricle). If this treatment is ineffective, three other invasive methods may relieve the obstruction.

  • The implantation of a pacemaker, a procedure that has a 30% success rate
  • Alcohol septal ablation (a catheter-based intervention), which creates a very localized infarct in the area where the muscle has thickened
  • Septal myectomy (a surgical procedure to resect the muscle)

In the case of cardiac arrhythmia (such as atrial fibrillation), other types of medications (anti-arrhythmic drugs) are used. If the risk of sudden death is considered high, a cardioverter defibrillator may be implanted in some patients.