Atrial fibrillation or AF can cause the heart to beat very fast. (CBC)

Up to 250,000 Canadians who have been diagnosed with a type of irregular heartbeat face up to five times greater risk of suffering a fatal stroke — a risk that can be dramatically reduced if medications are taken as prescribed, according to a report released Wednesday.

Atrial fibrillation, or AF, can cause the heart to beat very fast. After age 55, the incidence of AF doubles with each decade of life and other risk factors for heart disease and stroke, such as high blood pressure and diabetes, according to the Heart and Stroke Foundation.

"Stroke places a tremendous burden on our society," said Marco Di Buono, director of research for the Heart and Stroke Foundation of Ontario.

"When AF patients have a stroke, the impact becomes even more profound."

The impact of stroke in patients with AF include a higher risk of death, disability and muscular or cerebral consequences including another stroke, Di Buono added in an interview.

Up to 15 per cent of stroke patients have AF, according to data from several provinces that was analyzed by researchers at the Institute for Clinical Evaluative Sciences, an independent, non-profit organization in Toronto.

Blood thinners effective

The good news is that blood thinners like warfarin can dramatically reduce mortality rates from stroke in these patients, said Dr. Paul Dorian, a cardiologist and spokesman for the Heart and Stroke Foundation.

Fewer than half of AF patients over 65 in Canada who are prescribed blood thinners by specialists get the life-saving treatment and take it regularly, the group said.

Di Buono urged people who are diagnosed with AF and are prescribed blood thinners to talk to their family doctor about the potential benefits of the treatments.

Blood thinners or anticoagulants prevent clots from forming in the heart and travelling to the brain.

People who are taking blood thinners need to be monitored closely because they risk bleeding out if injured, and seniors are at greater risk of falls, Di Buono said.

All Canadians should know the warning signs of stroke and call 911 or their local emergency number if any of these signs occur:

• 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

People who have uncontrolled high blood pressure may go on to develop AF and should also be aware of its symptoms:

• Irregular and fast heartbeat.
• Heart palpitations or a rapid thumping in the chest.
• Chest discomfort.
• Chest pain or pressure.
• Shortness of breath, particularly with exertion.
• Anxiety, fatigue, dizziness, sweating, nausea, lightheadedness or fainting.

Healthy lifestyle changes that lower blood pressure, such as maintaining a normal weight, limiting salt intake and controlling diabetes, can help reduce the chances of developing atrial fibrillation.