title: Detection of occult atrial fibrillation in patients with embolic stroke of uncertain source: a work in progress.
abstract: Atrial fibrillation accounts for a substantial proportion of ischemic strokes of known etiology and may be responsible for an additional subset of the 25-40% of strokes of unknown cause (so-called cryptogenic). Oral anticoagulation is significantly more effective than antiplatelet therapy in the secondary prevention of atrial fibrillation-related strokes, providing justification for developing more sensitive approaches to detecting occult paroxysms of atrial fibrillation. In this article, we summarize the current state of knowledge regarding the value of in-hospital and out-patient monitoring for detecting atrial fibrillation in the context of cryptogenic stroke. We review the evidence for and against screening with standard Holter monitors, external loop recorders, the newer real-time continuous attended cardiac monitoring systems, cardiac implantable electronic devices, and insertable loop recorders. We review key questions regarding prolonged cardiac arrhythmia monitoring, including the relationship between duration of the atrial fibrillation episode and risk of thromboembolism, frequency of monitoring and its impact on the diagnostic yield in detecting occult or subclinical atrial fibrillation, and the temporal proximity of device-detected atrial fibrillation to stroke events. We conclude by proposing avenues for further research.
authors.affiliation: Electrophysiology Service, Department of Medicine, Montreal Heart Institute, Université de Montréal Montreal, QC, Canada ; Department of Medicine, Division of Cardiology, University of British Columbia Vancouver, BC, Canada.
authors.forename: Jason G
authors.initials: JG
authors.lastname: Andrade
authors.affiliation: Department of Medicine, Division of Neurology, University of British Columbia Vancouver, BC, Canada.
authors.forename: Thalia
authors.initials: T
authors.lastname: Field
authors.affiliation: Electrophysiology Service, Department of Medicine, Montreal Heart Institute, Université de Montréal Montreal, QC, Canada.
authors.forename: Paul
authors.initials: P
authors.lastname: Khairy
keywords: atrial fibrillation; implantable cardiac monitor; loop recorder; stroke; thromboembolism