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Signs of heart attack, cardiac arrest and sudden arrhythmia death syndrome (SADS)

Heart attack warning signs
Cardiac arrest signs
Sudden Arrhythmia Death Syndrome (SADS) warning signs

Heart attack warning signs

Thousands of Canadians die from heart attacks every year because they don't receive medical treatment quickly enough. Learn to recognize the signs of a heart attack so you can react quickly to save a life. Warning signs can vary from person to person and they may not always be sudden or severe. Although chest pain or discomfort is the most common symptom of a heart attack in both men and women, some people will not experience chest pain at all, while others will experience only mild chest pain or discomfort. Others may experience one symptom, while some experience a combination.

Pain Chest discomfort (uncomfortable chest pressure, squeezing, fullness or pain, burning or heaviness) Sweating Sweating
Discomfort in neck, jaw,shoulder, arms, back Discomfort in other areas of the upper body (neck, jaw, shoulder, arms, back) Nausea Nausea
Shortness of breath Shortness of breath Light headedness Light-headedness

If you are experiencing any of these signs, you should:

  • CALL 9-1-1 or your local emergency number immediately, or have someone call for you.
  • Keep a list of emergency numbers near the phone at all times.
  • Stop all activity and sit or lie down, in whatever position is most comfortable.
  • If you take nitroglycerin, take your normal dosage.
  • If the 9-1-1 operator advises it, chew and swallow one adult tablet or two 80 mg tablets of ASA (Aspirin®), as long as you are not allergic or intolerant. Do not take other pain medications such as acetaminophen (Tylenol®) or ibuprofen (Advil®) instead of Aspirin. Do not substitute Aspirin for medical care; call 9-1-1 or your local emergency number first.
  • Rest and wait for emergency medical personnel to arrive.

Heart attack emails
You may receive emails from well-meaning family and friends that claim to have authentic information about the signs and symptoms of heart attack or stroke. These messages usually contain incorrect information. Some may include a catchy phrase of signs to look for or certain activities to perform in order to prevent a heart attack or stroke. These messages only serve to confuse or cause delay in seeking help.

A heart attack or stroke is a very serious event that requires immediate medical attention. If you, or a loved one, suffer such an event, it is important to know the correct warning signs and how to act in order to get the best treatment available as early as possible.

The Heart and Stroke Foundation urges you not to circulate emails of this nature to your family and friends. Instead, become familiar with, and share the correct warning signs on our website at or Knowing these signs and calling 9-1-1, or your local emergency number immediately, is the most important thing you can do.

Cardiac arrest signs

Cardiac arrest is a medical emergency and can strike without warning, affecting people of all ages and all fitness levels.

Signs of a cardiac arrest include:

  • Sudden collapse.
  • Sudden unresponsiveness to touch or sound.
  • Abnormal or no breathing.

3 easy-to-follow steps if you witness someone having a cardiac arrest:

  1. Yell for help
    • Tell someone to call 9-1-1 or your emergency response number and get an AED (if one is available).
    • If you are alone, call 9-1-1 and get an AED (if one is available).
  2. Check breathing
    • If the person isn't breathing or is only gasping, give CPR.
  3. Push hard and push fast
    • Use an AED as soon as it arrives by turning it on and following the prompts.
    • Keep pushing until the person starts to breathe or move or someone with more advanced training takes over.

Sudden Arrhythmia Death Syndrome (SADS) warning signs

The most common warning signs for SADS are:

  • Fainting or seizure during physical activity.
  • Fainting or seizure resulting from emotional excitement, emotional distress, or being startled.
  • Family history of unexpected sudden death during physical activity or during a seizure, or any other unexplained sudden death of an otherwise healthy young person.

Although fainting is a relatively common occurrence, if it occurs in circumstances, such as during physical activity or from emotional excitement, it can represent a warning sign of SADS.

Click to learn about the
warning signs of stroke.

Last modified: April 2014
Last reviewed: April 2014