This approach uses stroke risk scores in a reductionist manner to aid decision-making, and balances simplicity and practicality (and costs). Recommendations 1. For patients with AF, including those with paroxysmal AF, stroke risk should be assessed using a risk factor based approach, rather than an categorization into low, moderate/high risk strata. We recommend use of the CHA2DS2-VASc as a simple clinical based stroke risk score to initially identify low stroke risk patients who should not be offered antithrombotic therapy to prevent stroke and reduce mortality (Strong recommendation, moderate quality evidence). Remark: Low risk patients are generally those age < 65 and lone AF irrespective of sex (this includes those with a CHA2DS2-VASc score 0 in males, or 1 in females). 2. Subsequent to this initial step, for patients with AF, including those with paroxysmal AF, stroke prevention should be offered to those AF patients with one or more non-sex CHA2DS2-VASc stroke risk factors (score of 1 in a male or 2 in a female) (Strong recommendation, moderate quality evidence). Remark: Consideration of other less established clinical stroke risk factors, imaging (cardiac or cerebral), or biomarkers (urine, blood, or genetics) may re ne risk strati cation based on simple clinical factors. A complex risk schema using a variety of such data that could accurately place more patients in the low risk stratum not requiring anticoagulants than current simple clinically based scores (personalized medicine) should be the goal of future research, but it will be very dif cult to nd non-anticoagulated patient cohorts for prospective validation. 