Risk factors for stroke and thromboembolism in patients with atrial fibrillation used in current risk stratification schema are derived largely from analyses of clinical trial cohorts, and the available data depend on the comprehensiveness of trial reports and whether specific risk factors were sought. The most commonly used schema is the Cardiac failure, Hypertension, Age, Diabetes, Stroke [Doubled] (CHADS 2 ) score. Although simple and well validated, some limitations of CHADS 2 this schema are apparent. A more recent approach to risk stratification of patients with nonvalvular atrial fibrillation defines "major (definitive)" risk factors (eg, previous stroke/transient ischemic attack and age Υ 75 years) and "clinically relevant non-major" risk factors (eg, heart failure, hypertension, diabetes, female gender, age 65-75 years, and atherosclerotic vascular disease). This scheme can be expressed as an acronym, CHA 2 DS 2 -VASc, denoting Cardiac failure or dysfunction, Hypertension, Age Υ 75 [Doubled], Diabetes, Stroke [Doubled]-Vascular disease, Age 65-74, and Sex category [Female]), whereby 2 points are assigned for a history of stroke or age 75 years or more and 1 point each is assigned for age 65 to 74 years, a history of hypertension, diabetes, cardiac failure, and vascular disease. Patients with 1 definitive risk factor or a patient with a CHA 2 DS 2 -VASc score of 1 or more could be considered for oral anticoagulation, but a patient with a CHA 2 DS 2 -VASc score of 0 is truly low risk and could be managed with no antithrombotic therapy. This would simplify our approach to thromboprophylaxis in patients with atrial fibrillation.