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Atrial fibrillation

Atrial fibrillation (Afib or AF) is a type of irregular heart rhythm (arrhythmia). Arrhythmias are due to electrical signal disturbances of the heart. Afib is the most common arrhythmia, affecting approximately 350,000 Canadians. The risk of developing atrial fibrillation increases with age and with other risk factors such as diabetes, high blood pressure and underlying heart disease. The main complications of atrial fibrillation are stroke and heart failure. People with atrial fibrillation have a risk of stroke that is 3 to 6 times greater than people without atrial fibrillation.

Atrial Fibrillation: Are you at risk of atrial fibrillation?


What is atrial fibrillation?

Atrial fibrillation affects the top two chambers of the heart (the atria). Arrhythmias can also occur in the two chambers below the atria (the ventricles), which tend to be more serious than arrhythmias affecting the atria.

The atria are the heart's collecting chambers. Regular electrical signals help push blood efficiently from the atria into the pumping chambers (the ventricles). From the ventricles, blood is pumped to the rest of the body. In Afib, the electrical signals are fast, irregular and disorganized, and the heart may not pump as efficiently.

Afib can cause your heart to beat very quickly, sometimes more than 150 beats per minute. A faster than normal heartbeat is known as tachycardia.

Most people with Afib lead active, normal lives with treatment, but untreated Afib can interfere with your quality of life. Talk to your doctor if you have Afib and continue to feel unwell.

1 in 3

One-third of all strokes after age 60 are caused by Afib.

Complications from Afib

Untreated atrial fibrillation puts you at a higher risk for stroke and heart failure.

People with atrial fibrillation have 3 to 6 times greater risk for ischemic stroke. During Afib, the atria contract chaotically. Because the atria aren’t moving blood properly, blood pools and gets stuck in the grooves of the heart. Blood clots may form, which could get pumped to the brain. An ischemic stroke is caused when blood flow to the brain is interrupted by a clot in a blood vessel in the brain. It is estimated that up to 15% of all strokes are caused by atrial fibrillation. The risk increases with age, so that after age 60 one-third of all strokes are caused by Afib.

The risk of stroke depends on several other risk factors including the presence of heart failure, having high blood pressure or diabetes, being over 65 years of age, or having had a previous stroke or a mini-stroke (TIA).

Studies show that long-term use of the blood thinner warfarin in patients with Afib can reduce the risk of stroke by 70 to 80%.

Atrial fibrillation can also lead to heart failure. Heart failure is a condition in which your heart can't circulate enough blood to meet your body's needs. Afib’s irregular, fast heart beat leads to ineffective pumping of the blood which – especially if not controlled – may weaken the heart.

Types of Afib

Paroxysmal: temporary episodes that come and go. They start suddenly and then the heart returns to a normal beat on its own without medical assistance, usually within 24 hours.

Persistent: episodes that last longer than seven days. Usually treatment is needed to return the heart to a normal rhythm.

Permanent: the irregular heart rhythm lasts for more than a year despite medications and other treatments. Some people with permanent Afib do not feel any symptoms or require medications.


Common causes of Afib include:

In many cases, the cause of atrial fibrillation is not known.

If you develop Afib before the age of 60 without any structural heart disease, you may have idiopathic (or lone) atrial fibrillation. Researchers have identified a handful of genes that predispose families to idiopathic Afib. It is also possible for young people without Afib in their family to develop the disease.


Some people with Afib may feel fine and not know they have the condition until it is found in a routine test called an electrocardiogram. Other people have symptoms. If you are experiencing any of these Afib symptoms, visit your doctor:

  • Irregular, fast heartbeat
  • Heart palpitations or a rapid thumping in the chest
  • Chest discomfort, chest pain or pressure
  • Shortness of breath, particularly with exertion or anxiety
  • Fatigue
  • Dizziness, sweating or nausea
  • Light-headedness or fainting

If you are experiencing chest discomfort or other signs of a heart attack , call 9-1-1 or your local emergency number immediately.

Ask your doctor to check your pulse on a regular basis.


If your pulse is fast and your heartbeat is irregular, your doctor may check you for Afib. They will take your medical history and question you about symptoms and risk factors.

Questions may include:

  • How long have you had symptoms? Describe them. Do they come and go?
  • Do you have other medical conditions?
  • How much alcohol do you drink?
  • Does anyone in your family have Afib?
  • Do you have heart disease or a thyroid condition?

Tests include:


Your treatment will be based on your risks, medical profile, needs, preferences and how much symptoms are interfering with your quality of life.

There are two general treatment strategies – rate control and rhythm control. Your doctor will determine which strategy is best for you based on your symptoms and other factors.

  • Rate control Almost every patient with atrial fibrillation will be prescribed a medication to slow their heart rate. For some people, this type of medication is enough to control their symptoms.
  • Rhythm control This is an attempt to prevent an irregular heartbeat by restoring and maintaining a normal, regular heartbeat. The first step is medication to prevent the Afib from occurring. Some patients may also require electrical cardioversion. This is a controlled electric shock to the heart to restore a normal rhythm. On rare occasions medications and electrical cardioversion do not work. You may be referred to a specialist and considered for an electrophysiology study and catheter ablation to stop the Afib from recurring.


When taking medications of any type, it is important to follow your doctor or pharmacist's instructions. Establish a routine for taking your pills and keep to your daily schedule. Do not share medications with others and do not stop taking your medication without consulting your doctor. Report any side effects to your doctor. They may change the dosage or type of medication to prevent or reduce side effects.

Make a list of all of your medications and always carry the list with you. Your pharmacy can print a list for you or use the chart in the medication chapter of the patient book Living Well with Heart Disease.

Surgeries and other procedures

  • Cardioversion therapy Electrical pulses are sent through paddles to the heart to jolt the heart back into normal rhythm. Cardioversion is similar to defibrillation, but uses much lower levels of electricity.
  • Electrophysiology Studies (EPS) and Catheter Ablation Some people with Afib – who do not respond to medications or electrical cardioversion – require an EPS to stop Afib from recurring. EPS testing is used to locate the site of the irregular electrical impulses in the heart. Catheter ablation is then performed to destroy – through tiny burns – the electrically chaotic heart tissue. Ablation creates scars in the heart that stabilize the electrical short circuits.
Living with Atrial Fibrillation

Mel, Christine and others tell their story of Afib

Visit your doctor regularly to have your Afib monitored.

Living a healthy lifestyle is always a good idea.

If you have Afib, staying physically active will have a positive impact on your overall health. Consult your doctor before you become more physically active.

If you have high blood pressure, ask your doctor how to monitor your own blood pressure at home.

Related information

Atrial Fibrillation Ablation (Hamilton Health Sciences)

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