Searching for Atrial Fibrillation Poststroke: A White Paper of the AF-SCREEN International Collaboration

Cardiac thromboembolism attributed to atrial fibrillation (AF) is responsible for up to one third of ischemic strokes. Stroke may be the first manifestation of previously undetected AF. Given the efficacy of oral anticoagulants (OAC) in preventing AF-related ischemic strokes, strategies of searching for AF post-stroke using ECG monitoring followed by OAC treatment, have been pro-posed to prevent recurrent cardioembolic strokes. This white paper by experts from the AF-SCREEN International Collaboration summarizes existing evidence and knowledge gaps on searching for AF post-stroke using ECG monitoring. New AF can be detected by routine plus intensive ECG monitoring in approximately one quarter of patients with ischemic stroke. It may be causal, a bystander, or neurogenically-induced by the stroke. AF post-stroke is a risk factor for thromboembolism and a strong marker for atrial myopa-thy.After acute ischemic stroke, patients should undergo 72 hours of electrocardiographic monitoring to detect AF. The diagnosis requires an ECG of sufficient quality for confirmation by a health pro-fessional with ECG rhythm expertise. AF detection rate is a function of monitoring duration and quality of analysis, AF episode definition, interval from stroke to monitoring commencement, and patient characteristics including old age, certain ECG alterations, and stroke type. Markers of atrial myopathy (e.g. imaging, atrial ectopy, natriuretic peptides) may increase AF yield from mon-itoring, and could be used to guide patient selection for more intensive/prolonged post-stroke ECG monitoring. Atrial myopathy without detected AF is not currently sufficient to initiate OAC.The concept of ESUS (Embolic Stroke of Unknown Source) is not proven to identify stroke pa-tients benefitting from empiric OAC treatment. However, some ESUS sub-groups (e.g. advanced age, atrial enlargement) might benefit more from Non-Vitamin K-dependent OAC (NOAC) therapy than aspirin. Fulfilling ESUS criteria is neither an indication for empiric NOAC treatment nor for withholding prolonged ECG monitoring for AF.Clinically diagnosed AF after stroke/transient ischemic attack (TIA) is associated with significantly increased risk of recurrent stroke or systemic embolism, in particular with additional stroke risk factors, and requires OAC rather than antiplatelet therapy. The minimum subclinical AF duration required on ECG monitoring post-stroke/TIA to recommend OAC therapy is debated