Cardiovascular Diseases



Dilated Cardiomyopathy


In dilated cardiomyopathy (CMP), the muscle of the left (or right) ventricle becomes weak and the heart cavity dilates, which decreases the heart muscle's strength of contraction. The result is a smaller ejection fraction, or the amount of blood forced out of the heart with each beat.

Causes and/or risk factors 

The most common causes of dilated cardiomyopathy are alcohol abuse, infections (viral or bacterial), diabetes, some endocrine diseases, some chemotherapy medications and other drugs (such as cocaine). In approximately half of cases, there is no specific cause, which is referred to as idiopathic dilated cardiomyopathy.

Approximately 20% of patients with dilated cardiomyopathy may have a familial form associated with a mutation in their DNA.


Patients with dilated cardiomyopathy may experience heart failure symptoms, which are:

  • Shortness of breath upon exertion or at rest
  • Orthopnea (difficulty lying flat on one's back; a few pillows are required for a comfortable sleeping position)
  • Paroxysmal nocturnal dyspnea (waking up in the middle of the night out of breath)
  • Fatigue, decreased exercise capacity
  • Swelling in the lower limbs (edema) or stomach

However, some patients have no symptoms and are only diagnosed with dilated cardiomyopathy during a routine or screening exam.


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

To eliminate a specific cause of dilated cardiomyopathy, the doctor may order:

  • Cardiac magnetic resonance imaging
  • Coronary angiography
  • A biopsy of the heart muscle

Finally, if the doctor suspects that the dilated cardiomyopathy has a genetic cause, he or she may recommend a consultation at the Genetics Centre, where staff will conduct:

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

The basic treatment for dilated cardiomyopathy is to deal with the underlying cause once it is identified (e.g., through alcohol cessation). In all cases, the doctor will prescribe the usual medications to treat heart failure.

A cardioverter defibrillator implantation may also be indicated if the patient has an increased risk of sudden death because of a very low ejection fraction or if the person has a family member who died of cardiomyopathy at a young age.