In this section, we summarize the evidence and give treatment recommendations for VKA therapy, antiplatelet monotherapy (eg, aspirin), dual antiplatelet therapy with aspirin and clopid- ogrel, and new oral anticoagulants (eg, dabigatran) in patients with AF. 2.1 Patients With Nonrheumatic AF 2.1.1 VKAs vs No Therapy: Six RCTs that enrolled a total of 2,584 patients and address the primary pre- vention (Atrial Fibrillation Aspirin and Anticoagulation [AFASAK] 1, Boston Area Anticoagulation Trial for Atrial Fibrillation [BAATAF], Canadian Atrial Fibril- lation Anticoagulation [CAFA], Stroke Prevention in Atrial Fibrillation [SPAF] I, Stroke Prevention in Nonrheumatic Atrial Fibrillation [SPINAF]) and sec- ondary prevention (European Atrial Fibrillation Trial [EAFT]) of stroke in patients with AF provide high- quality evidence that VKA therapy reduces the risk of death by one-fourth and the risk of nonfatal stroke by two-thirds compared with no therapy (Table 3).55-61 For patients with a CHADS2 score of 0, the studies provide moderate-quality evidence that VKA therapy increases the risk of nonfatal major extracranial bleeding due to imprecision of the esti- mate (wide CIs). The studies provide high-quality evidence for patients with higher CHADS2 scores. risk factors: female sex, age 65 to 74 years, and vascular disease (de ned as a history of MI, peripheral arterial disease, or complex aortic plaque). The CHA2DS2-VASc score has been evaluated in at least ve separate cohorts since its original description. 