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Saturday, June 28, 2014

Fending Off Second Strokes

"These are often tragic strokes that can impair memory, language and other cognitive functions and result in permanent disability."
"We want to do the utmost to improve stroke prevention and one way to do that is by early detection and treatment of atrial fibrillation."
"We regularly see patients with warning strokes of transient ischemic attacks -- mini strokes -- for which there is no obvious cause found."
"[In 'cryptogentic' strokes] patients undergo all the standard diagnostic tests and they all come back 'normal'. The underlying cause of the stroke remains a mystery."
Dr. David Gladstone, director, Regional Stroke Prevention Clinic, Sunnybrook Health Sciences Centre, Toronto
photo of Dr. David Gladstone
Dr. David Gladstone led the EMBRACE trial (photo by Doug Nicholson/Media Source)

The world's largest heart monitoring study of stroke patients, undertaken by Canadian researchers and led by Dr. Gladstone, an associate professor in the department of medicine at University of Toronto, has led to a discovery of a novel way to detect abnormal and erratic heart rhythms in stroke survivors. Those abnormalities increase risk for a second and potentially lethal brain attack.

The findings are expected to alter standards of care for the thousands of Canadians who suffer unexplained strokes annually.

The study took in 15 medical centre practices and patient out come statistics and concluded with a new strategy to use a continuous, 30-day heart monitoring protocol, one which found five times as many cases of atrial fibrillation than did the standard 24-hour test. The results were published this week in the New England Journal of Medicine.

Atrial fibrillation
In atrial fibrillation, arrhythmia (irregular heartbeat or heart rhythm) occurs because the electrical signal controlling the heartbeat becomes confused, and the atria quiver rapidly and unevenly, changing the constant rhythm of the heart.

The atria and ventricles no longer work in a coordinated way to contract and pump blood, the heart may not pump blood efficiently, and the heart rhythm becomes abnormal. In AF, the heart beats about 100 to 175 times per minute.
Atrial fibrillation, also termed AF, is a condition where the heart quivers, beating chaotically. The result of which can be blood pooling in the upper left chamber of the heart, a venue where clots may form, then travel through the circulation system into the brain. Those suffering from AF have a three- to-five-times higher stroke risk than people without the condition.

Resulting strokes are more devastating and deadly than strokes emanating from other causes. People who suffer an AF-related stroke are 70% to 80 percent more likely to die or become disabled. While some of these events can result in "instantaneous dementia", according to researchers, where permanent disability results from disruption of cognitive functioning.

AF is considered a silent killer; whose symptoms are difficult to detect. And unless people experience recognizable symptoms like flutterings of the heart, skipped heartbeats, or shortness of breath, the condition can be easily missed. Standard treatment for "cryptogenic" strokes is generally the prescription of low-dose Aspirin in hopes of preventing a second stroke from occurring.

"But if the person has AF that might not be strong enough", stated Dr. Gladstone, in which case more effective anti-clotting drugs can be prescribed to lessen the risk of a second stroke occurring, by 50% or even greater. The study involved 572 patients aged 55 and older without a history of AF. All patients were given the conventional protocol of 24-hour monitoring where AF wasn't revealed to be present.

Following that, patients were selected for two randomized groups. One group received an additional 24 hours of the standard monitoring which uses a small device that clips on a belt with wires taped to the torso, while the second group received prolonged monitoring with the use of an electrode belt worn around the chest. Patients were requested to wear the monitor for 30 consecutive days.

The result was that AF was detected in 16 percent of the patients in the 30-day group as opposed to three percent detected in the 24-hour group. This has led to an obvious conclusion, that twice as many patients as formerly could be prescribed stronger medications to deal with their detected greater potential to suffer a second, dangerous stroke.

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