Cardiovascular Diseases



Acute coronary syndrome


Also known as unstable angina, myocardial infarction

Stable angina may become unstable, or coronary artery disease may first manifest as acute coronary syndrome (ACS). In this situation, a clot (thrombus) forms on the atherosclerotic plaque that is partially or completely obstructing the artery. The heart muscle suddenly lacks oxygen, which results in unstable angina (if the heart muscle has not suffered irreversible damage) or infarction (if there is irreversible damage, unless treated immediately).

Very rarely, myocardial infarction may occur in a patient whose coronary arteries are free of atherosclerosis. The coronary artery may be blocked by a clot from a heart cavity (atrium or from the left ventricle) or from a prosthetic valve. The artery may also undergo acute narrowing (spasm) that is often caused by the use of drugs such as cocaine.

Causes and/or risk factors 

The risk factors are diseases or characteristics that promote the onset and accelerate the progression of arteriosclerosis. These are:


Acute coronary syndrome symptoms can vary from person to person, but they are generally quite intense and unpredictable. They may occur upon effort or at rest and sometimes during sleep. Nitroglycerin or cessation of the activity provides little or no relief. When in doubt, an immediate consultation at the emergency room of the closest hospital will exclude or confirm an ACS diagnosis, and the patient can then start an appropriate treatment.

The most frequent symptoms are:

  • Chest pain in the form of a tightening, burning, weight, etc.
  • Pain that may radiate to the neck, jaw, shoulders and back.
  • These symptoms may be associated with shortness of breath, nausea or vomiting, dizziness or loss of consciousness.

A diagnosis of acute coronary syndrome is generally made with:

  • An ECG
  • Blood tests

If the pain is very recent or if only a limited part of the heart muscle is affected, these two tests may need to be repeated in the hours following the patient's arrival to the hospital to confirm or exclude the diagnosis of acute coronary syndrome.


Optimal blood pressure control, Holter monitoring to detect and treat heart arrhythmia, and medications to thin the blood and decrease the heart's workload are part of basic acute coronary syndrome treatment. Depending on the patient's condition and the analysis of initial exams, other tests and treatments may be prescribed, such as:

  • Coronary angiography, which may or may not be combined with coronary dilatation or coronary stent placement

Before discharge, other tests may also be conducted to determine the scope of the heart damage and the patient's ability to return to normal activities.

Living with the disease 

Upon discharge, medical and nursing staff determine how the patient can best return to normal life depending on the degree of heart damage and the patient's history. It is important for patients with acute coronary syndrome to work with their doctors on the risk factors listed above. Quitting smoking, reaching a healthy weight, eating a healthy diet and following an adapted exercise program are part of treatment, which also includes taking medication to treat high blood pressure or diabetes. These recommendations are applicable for people who want to avoid developing coronary atherosclerosis (primary prevention) and for people who have already been diagnosed with this condition (secondary prevention). For more information on preventing heart disease by working on your risk factors, refer to the section on Prevention.