Background-The aims of the present study were to define the prevalence of untreated atrial fibrillation (AF) in a systematic screening program using intermittent ECG recordings among 75-to 76-year-old individuals and to study the feasibility of initiating protective oral anticoagulant (OAC) treatment. Methods and Results-Half of the 75-to 76-year-old population in 2 Swedish regions were invited to a screening program for AF. Participants without a previous diagnosis of AF underwent intermittent ECG recordings over 2 weeks. If AF was detected, participants were offered OAC. During the 28-month inclusion period, 13 331 inhabitants were invited. Of these, 7173 (53.8%) participated. Of the participants, 218 (3.0%; 95% confidence interval [CI], 2.7-3.5) were found to have previously unknown AF, and of these, AF was found in 37 (0.5% of the screened population) on their first ECG. The use of intermittent ECGs increased new AF detection 4-fold. A previous diagnosis of AF was known in 9.3% (n=666; 95% CI, 8.6-10.0). Total AF prevalence in the screened population was 12.3%. Of participants with known AF, 149 (2.1%; 95% CI, 1.8-2.4) had no OAC treatment. In total, 5.1% (95% CI, 4.6-5.7) of the screened population had untreated AF; screening resulted in initiation of OAC treatment in 3.7% (95% CI, 3.3-4.2) of the screened population. More than 90% of the participants with previously undiagnosed AF accepted initiation of OAC treatment. Conclusions-Mass

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Approximately 10% of ischemic strokes are associated with atrial fibrillation (AF) first diagnosed at the time of stroke. Detecting asymptomatic AF would provide an opportunity to prevent these strokes by instituting appropriate anticoagulation. The AF-SCREEN international collaboration was formed in September 2015 to promote discussion and research about AF screening as a strategy to reduce stroke and death and to provide advocacy for implementation of country-specific AF screening programs. During 2016, 60 expert members of AF-SCREEN, including physicians, nurses, allied health professionals, health economists, and patient advocates, were invited to prepare sections of a draft document. In August 2016, 51 members met in Rome to discuss the draft document and consider the key points arising from it using a Delphi process. These key points emphasize that screen-detected AF found at a single timepoint or by intermittent ECG recordings over 2 weeks is not a benign condition and, with additional stroke factors, carries sufficient risk of stroke to justify consideration of anticoagulation. With regard to the methods of mass screening, handheld ECG devices have the advantage of providing a verifiable ECG trace that guidelines require for AF diagnosis and would therefore be preferred as screening tools. Certain patient groups, such as those with recent embolic stroke of uncertain source (ESUS), require more intensive monitoring for AF. Settings for screening include various venues in both the community and the clinic, but they must be linked to a pathway for appropriate diagnosis and management for screening to be effective. It is recognized that health resources vary widely between countries and health systems, so the setting for AF screening should be both country- and health system-specific. Based on current knowledge, this white paper provides a strong case for AF screening now while recognizing that large randomized outcomes studies would be helpful to strengthen the evidence base.