Improved detection of atrial fibrillation through new devices could prevent a significant number of disabling strokes

A clinical trial examining the efficacy of two devices to monitor and detect atrial fibrillation (AF), or an irregular heartbeat, in ischemic stroke patients—one an implantable device that monitors over 12 months, the other an external device that monitors over a 30-day period—found the implantable device is more than three times more effective in detecting AF, and both are a significant improvement over the current standard of care in Alberta.

The Post-Embolic Rhythm Detection With Implantable Versus External Monitoring (PER DIEM) study, led jointly by University of Alberta and University of Calgary researchers, was published today in the journal JAMA. The findings are expected to significantly change practice in how clinicians look for AF in Albertan patients following ischemic stroke.

“We know that (the current method of monitoring) isn’t as effective as it could be in picking up atrial fibrillation from this study because regardless of which arm of the study patients went into, we were picking up anywhere from five to 15 per cent extra atrial fibrillation,” said Brian Buck, a stroke neurologist and associate professor of medicine at the U of A. “We found in the study there were a lot of patients with undetected atrial fibrillation, even after they received the standard cardiac monitoring.”

Atrial fibrillation causes about one in four strokes in Alberta. Detecting it early is key to preventing further disabling strokes in patients who have already experienced ischemic stroke, a type of stroke caused by a blockage in an artery that supplies blood to the brain. If atrial fibrillation is detected, clinicians have treatments—mainly blood thinners—that can reduce the risk of stroke by almost 70 per cent.

The standard test in Alberta for AF is a 24-hour electrocardiogram monitor. In the PER DIEM trial, 300 Albertan patients who had suffered a stroke were randomized to one of two new devices that can monitor for AF for longer durations. The study showed that the implantable device picked up three times more new AF than the 30-day monitor (15 per cent versus five per cent). All of the patients in the clinical trial with new AF were started on blood thinners.

“We didn’t expect that we would get such a dramatic increase with the longer recording, even though it intuitively makes sense,” said study co-author Michael Hill, professor of neurology at the University of Calgary and senior medical director for stroke with Alberta Health Services’ Cardiovascular and Stroke Strategic Clinical Network. “Most people suspected that detection rates apply to only certain subtypes of ischemic stroke. This study showed that theory is not correct.”

“We believe that those patients that were identified with atrial fibrillation are now, for the rest of their lives, going to have a much lower risk of having a stroke in the future,” added Buck, who is also a member of the U of A’s Neuroscience and Mental Health Institute.

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