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30-Day Cardiac Event Monitor Belt for Recording Atrial Fibrillation After a Cerebral Ischemic Event (EMBRACE): A Randomized Controlled Trial
David Gladstone, University of Toronto
Paul Dorian, University of Toronto
Melanie Spring, University of Toronto
Martin O’Donnell, McMaster University
Muhammad Mamdani, University of Toronto
Kevin Thorpe, University of Toronto
Andreas Laupacis, University of Toronto
Moira Kapral, University of Toronto
Richard Aviv, University of Toronto
John Blakely, University of Toronto
Robert Côté, McGill University
Mike Sharma, University of Ottawa
Ashfaq Shuaib, University of Alberta
Atrial fibrillation (AF), the most common heart rhythm disorder in medical practice, is dangerous because it can lead to blood clots in the heart that can travel to the brain and cause stroke. Therefore, most patients who are recognized to have a stroke or “mini stroke” (TIA) caused by AF can benefit from the blood thinner warfarin to protect against recurrent strokes (warfarin reduces stroke risk by 67%). Without warfarin, the risk of recurrent strokes is high.
An unsolved problem is how to best diagnose AF because it is often intermittent and asymptomatic. Current methods for diagnosing AF are inefficient: most patients receive only a 24- or 48-hour heart rhythm recording (Holter monitor) and unless the AF occurs during the monitoring period, the diagnosis is missed, warfarin is not given, and a proportion of patients experience a recurrent stroke. An innovative new technology is now available to enable monitoring of patients for substantially longer periods. It is hypothesized that 30-day monitoring shortly after a stroke or TIA will be able to detect more patients with AF than a standard 24-hour monitor and prevent recurrent strokes.
EMBRACE is the largest study of its kind and the first randomized controlled trial to determine the optimal diagnostic strategy for detecting AF in stroke/TIA patients. Patients with a recent ischemic stroke/TIA of uncertain cause (“cryptogenic”), no known history of AF, and for whom the standard tests (ECG and Holter) have not revealed AF will be enrolled in the study. Half the patients will be randomly assigned to a 30-day electronic study monitor (experimental group) and half will be assigned to a repeat 24-hour Holter monitor (control group). The study monitor is programmed to automatically record episodes of AF. It is attached to a soft, lightweight elastic belt that is easily worn under clothing around the chest; it does not require electrodes that stick to the skin, so it is more comfortable than current monitors. The study will enroll 578 patients from 17 Canadian stroke centres over 2 years.