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

Signs of heart attack
Signs of cardiac arrest
Signs of Sudden Arrhythmia Death Syndrome (SADS)

Signs of heart attack

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.
  • Chew and swallow one adult tablet (325 mg) or two 81 mg tablets of ASA (Aspirin®), as long as you are not allergic or intolerant. If you are having a heart attack, chewing and swallowing ASA at the first sign can reduce your risk of dying by helping to stop blood clots from forming in the arteries. Do not take other pain medications such as acetaminophen (Tylenol®) or ibuprofen (Advil®) instead of ASA. Do not substitute ASA 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.

Signs of cardiac arrest

Cardiac arrest is a medical emergency and can strike without warning, affecting people of all ages and all fitness levels. It is an electrical problem, usually resulting from a disruption of the heart’s normal rhythm. During cardiac arrest the heart stops beating effectively.

Signs of a cardiac arrest include:

  • Sudden collapse.
  • Sudden unresponsiveness to touch or sound.
  • No breathing or abnormal breathing or gasping.

Easy-to-follow steps: Hands-Only* CPR

If you witness someone having a cardiac arrest:
  1. Call 9-1-1
    • Don’t delay – ACT! If someone is nearby, tell them to phone 9-1-1 and get an AED.
    • If you are alone and have a mobile phone, use it to phone 9-1-1 and put the phone on speaker mode to speak with the dispatcher.
  2. Push hard and fast in the centre of the chest (start CPR)
    • Push hard and fast to the beat of “Staying Alive”; or about 100-120 times per minute.
    • Don’t stop until someone else can take over or the person begins to respond.
  3. Use an AED (if one is available)
    • Use it as soon as it arrives.
    • AEDs are safe and simple to use. Turn it on and it will provide voice instructions that tell you everything you need to do.

*Hands only is a servicemark of the American Heart Association, Inc., used under license.

Signs of Sudden Arrhythmia Death Syndrome (SADS)

The most common 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
signs of stroke.

Last modified: October 2016
Last reviewed: October 2016