Compared with usual care, implantable cardiac monitors (ICM) detected significantly more atrial fibrillation (AF) events in stroke patients who likely would not have been monitored long term for AF otherwise, according to a study published recently in JAMA.

The trial, Stroke of Known Cause and Underlying Atrial Fibrillation, STROKE-AF trial for short, looked at patients who just experienced an ischemic stroke attributed to cervical or intracranial large-artery atherosclerosis or small-vessel occlusion.

Of the nearly 500 patients in the trial, AF was detected in 12.1% of the patients with ICM, compared with 1.8% of patients with the usual care of external cardiac monitoring, such as 12-lead electrocardiograms, Holter monitoring, telemetry or event recorders.

Given that almost a quarter of strokes in the U.S. are recurrent, identifying AF in patients is crucial to secondary stroke prevention and could inform the level of AF activity that requires oral anticoagulation therapy. Moreover, patients who had a large- or small-vessel disease-related stroke are still at risk for an AF-related stroke, especially if they are receiving only antiplatelet therapy.

“Ischemic stroke patients with large- or small-vessel disease haven’t been considered at high risk for atrial fibrillation. Until now, we didn’t have good data on the frequency of atrial fibrillation in these patients,” said Nadeem A. Talpur, M.D., a stroke neurologist at Norton Neuroscience Institute and one of the principal investigators in the clinical trial. “This data shows these patients are significantly more likely to have A-fib [atrial fibrillation] incidents than had been thought and that further research is warranted to determine how we might use that information in a clinical setting.”

STROKE-AF trial volunteers were split randomly between receiving ICM or usual care monitoring. Patients in the ICM group received the implant within 10 days of the stroke.

“The importance of detecting AF is not to ascribe an alternative etiology to the index stroke, but rather that it represents a risk for future cardioembolic stroke, which may be more effectively prevented by OAC [oral anticoagulant] than antiplatelet therapy,” according to “Effect of Long-term Continuous Cardiac Monitoring vs. Usual Care on Detection of Atrial Fibrillation in Patients With Stroke Attributed to Large- or Small-Vessel Disease: The STROKE-AF Randomized Clinical Trial.”