Learn more about strokes, stroke causes, why strokes are more likely in people with AFib, and why it's so important to reduce your risk.

What is a stroke?

A stroke is a sudden interruption of blood flow to the brain. Without the oxygen and nutrients carried by the blood, brain cells begin to die. The longer blood flow is interrupted, the greater the risk of permanent brain damage and death.

There are two common types of stroke:

Type of stroke What happens
Ischemic stroke (80% of strokes)

A blood clot blocks blood flow to the brain. Ischemic strokes may be:

  • thrombotic: A blood clot forms in a blood vessel in the brain and blocks it.
  • embolic: A blood clot forms in another part of the body (such as the heart), moves into the brain, and blocks a blood vessel.
Hemorrhagic stroke (20% of strokes) Blood vessels rupture in the brain, causing blood to leak out. The leaking blood and the interruption of normal blood flow damage the brain.

Depending on the part of the brain affected, strokes can affect your vision, mobility, thoughts, memory, and speech. See "How could a stroke affect my health and lifestyle?" to learn more.

Some people may have a "mini-stroke," also called a TIA (transient ischemic attack). With a TIA, the blood flow to the brain is temporarily blocked. A TIA causes the same symptoms as a stroke, but the symptoms usually disappear within 24 hours. However, a TIA is still very serious because it could still cause brain damage, and because it is a warning that you are at risk of a stroke.

What is AFib?

AFib, or atrial fibrillation, causes an irregular heartbeat. It the most common type of irregular heartbeat, affecting about 350,000 Canadians.

Here's how the heart normally works:

The heart is a large muscle with 4 chambers: the top chambers are called the atria and the bottom chambers are called the ventricles. Normally, the atria and ventricles work together. First the atria contract (this means that the muscle squeezes) and pump blood into the ventricles, then the ventricles contract and pump blood through the body. This process is controlled by electrical signals in the heart. Normally, the atria pump regularly with a constant rhythm.

Here's what happens with atrial fibrillation:

The heart's electrical signals become disorganized, and the atria don't contract in a regular rhythm. Instead they quiver or contract in an unpredictable way, which means that the heart pumps less efficiently. The heartbeat becomes rapid and irregular.

Watch the "Healthy Heart" and " Atrial Fibrillation Heart" videos to see the difference between a normal heartbeat and an AFib heartbeat.

Learn more about the different forms of AFib at StrokeandAF.ca.

AFib may cause symptoms* such as:

  • palpitations (an irregular and rapid heartbeat, typically experienced as a rapid thumping in the chest)
  • chest pain or discomfort
  • shortness of breath, especially when you are physically active
  • fatigue, nausea, or sweating
  • dizziness or light-headedness

*This list includes common AFib symptoms but is not a complete list of all possible symptoms. Some people may have additional AFib symptoms not listed above.

But sometimes AFib causes no symptoms at all.

AFib greatly increases the risk of stroke, but the good news is that there are many things you can do to lower your risk of stroke.

How does AFib increase my stroke risk?

With AFib, your risk of a stroke caused by a blood clot is 3 to 5 times what it would be otherwise. AFib is associated with up to 15% of all strokes overall, and one-third of strokes in people over 60.

Why are people with AFib so likely to have a stroke?

With AFib, the heart beats in an irregular, disorganized way.
Blood pools in the heart.
A blood clot forms in the heart.
The blood clot travels through the bloodstream to the brain.
The blood clot blocks a blood vessel in the brain, cutting off blood flow to the brain and causing a stroke.

This type of stroke, where a blood clot blocks a blood vessel in the brain, is called an ischemic stroke. Ischemic strokes are the most common type of stroke: about 80% of all strokes are ischemic.

Learn more about the link between AFib and stroke (select the video "Stroke and Atrial Fibrillation").

How big is your risk of stroke? Use the stroke risk calculator to find out.

What are the symptoms of a stroke?

Stroke warning signs

Learn to recognize the warning signs of stroke. If you see them, respond immediately by calling 9-1-1 or your local emergency number. It can significantly improve survival and recovery.

Weakness - Sudden loss of strength or sudden numbness in the face, arm or leg, even if temporary.
Trouble speaking - Sudden difficulty speaking or understanding or sudden confusion, even if temporary.
Vision problems -Sudden trouble with vision, even if temporary.
Headache - Sudden severe and unusual headache.
Dizziness - Sudden loss of balance, especially with any of the above signs.

If you experience any of these symptoms, call 9-1-1 or your local emergency number immediately.

© Reproduced with the permission of the Heart and Stroke Foundation of Canada, 2011.

Print the stroke warning signs and put them on your fridge or in your wallet.

This list includes common stroke warning signs but is not a complete list of all possible warning signs. Some people may have additional warning signs not listed above.

How could a stroke affect my health and lifestyle?

The effects of a stroke vary from person to person: some people die, others recover completely, but many have effects that could last a lifetime.

Here's what could happen to you after a stroke:

Death 15%
Very severe disability (you will need long-term care) 10%
Moderate-to-severe disability (you can function on your own but with difficulty) 40%
Mild disability (your disability is inconvenient but does not have a major impact on your life) 25%
Complete recovery 10%

A stroke can affect many different parts of your life, depending on the areas of the brain that were damaged:

Type of problem What could happen? How could this affect my life?
Physical problems

You could have weakness or paralysis along one side of your body, painful muscle spasms, vision changes (double vision or "blind spots"), difficulty swallowing, constant pain, poor balance, or a loss of fine motor skills (the ability to make small, precise movements).

It might be harder for you to get around and do your usual activities.
Mental challenges

You could have trouble speaking, understanding speech, remembering recent events, or learning and remembering new information.

You could also have personality changes, poor judgment, and impulsive behaviour.
It could be harder for you to do your job and function day to day.
Emotional changes

You may also feel frustrated, angry, depressed, or emotionally out of control.

This could put a strain on your relationships.

Some of these problems may improve over time. Stroke rehabilitation can help people regain some of the function they have lost and live life to the fullest.