Just a quivering heartbeat away from stroke

When walking up the stairs at home to get ready to go run some errands, Gordon MacKay noticed he was out of breath and a little weak, which was unusual for the healthy 54-year old. Then, just as he was pulling on his boots to go out the door, the strength drained right out of him − so much so that he could barely sit up. He felt his heart beating out of control. "It was very scary," Gordon says. His wife Claudette called an ambulance.

At the hospital, doctors diagnosed Gordon with atrial fibrillation, a condition involving an irregular heartbeat, also known as arrhythmia. Atrial fibrillation is the most common type of arrhythmia, affecting approximately 250,000 Canadians. While it is rare in people under 40, its prevalence increases with age. About 3% of the population over the age of 45 and 6% over age 65 have atrial fibrillation.

During atrial fibrillation, the upper chambers of the heart known as the atria contract chaotically and in a disorganized manner. Instead of beating normally and efficiently, the atria quiver. Because the atria can't move blood properly, blood pools and gets stuck in the grooves of the heart. Clots can form in this pooled blood, which may get pumped up to the brain and cause a stroke.

It is estimated that up to 15% of all strokes are due to atrial fibrillation (AF). This risk increases with age, so that after age 60, one-third of 50,000 strokes that occur in Canada are due to AF.

Gordon has been lucky that his condition has not led to a stroke. Foundation researcher, Dr. Michael Gollob, says that this is partially because Gordon was able to recognize something was wrong before the problem got worse. "Some people with AF never notice any symptoms. Sometimes the heartbeat is irregular, but not excessively fast. People who get a more rapid heart rate are more likely to notice symptoms and get help. But whether or not that person notices the symptoms, the risk of stroke is always there," says Dr. Gollob. The good news is that once it is diagnosed, there are treatments that can help.

The shortness of breath and weakness some people experience are usually caused by a racing heartbeat (also called tachycardia) that occurs in some people with AF, he says. Also, that kind of heartbeat feels different: "Usually, the elevated heart rate is very noticeable," Dr. Gollob says. It's not like what happens after drinking too much coffee or during stressful periods, he explains. "It's quite rapid and the symptoms occur at rest when they haven't been exerting themselves very much, if at all." However, in some people, heart rate may fall within normal range. It may even be slower than normal.

For some, there are no symptoms. But others with AF may experience:

• 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, or anxiety
• fatigue
• dizziness, sweating, nausea
• lightheadedness or fainting

Once a diagnosis of AF has been made, there are ways to control the condition and reduce the risk of stroke. Medication is usually the first approach. In Gordon's case, he was immediately put on a drug in hospital to try to slow his heartbeat, but it didn't have the desired effect. So, the doctors performed a cardioversion procedure, in which the heart is shocked back into its normal rhythm. "When it was over," says Gordon, "I felt right as rain and I walked out of the hospital, happy to see the blue sky again."