A significant portion of people with unexplained strokes has silent atrial fibrillation, researchers in 16 Canadian stroke centres discovered as part of the largest study and first randomized clinical trial of heart monitoring in stroke patients.
Atrial fibrillation, an irregular heart rhythm, is known to cause some of the most disabling, deadliest, and most costly types of strokes, but it can be a silent risk factor that evades detection.
The three-year trial involving 572 patients was presented February 7, 2013 at the International Stroke Conference by lead researcher Dr. David Gladstone, director of the Regional Stroke Prevention Clinic at Sunnybrook, and assistant professor in the Department of Medicine at University of Toronto.
He reported that with a new strategy of advanced heart monitoring, one in six people with an unexplained stroke or transient ischemic attack (TIA) were found to have silent atrial fibrillation that would have otherwise gone undiagnosed and untreated by standard methods.
"This study provides the strongest evidence to date to support intensive heart monitoring in patients with unexplained strokes or mini-strokes," according to the American Stroke Association, which highlighted the Canadian research as a late-breaking research development at the meeting.
Atrial fibrillation is a risk factor for stroke because it can promote the formation of blood clots in the heart that can travel to the brain. It is important to detect because it can be effectively treated with certain anti-clotting medications, which cut the risk of clots and strokes by two-thirds or more.
The challenge has been that atrial fibrillation is often hard to detect because the irregular heartbeat may last for just a few minutes at a time, after which the heart reverts back to its normal rhythm. Unless an individual is wearing a heart monitor at the time it occurs, the diagnosis is usually missed. In practice, stroke patients have traditionally received short-duration heart monitoring for 24 or 48 hours to screen for atrial fibrillation. However, advances in heart monitoring technology now make it possible for patients to be screened at home for much longer periods.
"The hope is that earlier detection and treatment of atrial fibrillation may lead to more strokes prevented and more lives saved," said Dr. Gladstone.