The CHADS2 versus the New CHA2DS2-VASc Scoring Systems for Guiding Antithrombotic Treatment of Patients with Atrial Fibrillation: Review of the Literature and Recommendations for Use

The association of atrial fibrillation and resultant thromboembolic stroke is readily recognized in the published literature. However, the identification and weight of other risk factors that increase stroke risk are varied. To predict which patients are at greatest risk for thromboembolic stroke, numerous risk stratification schemas have been developed to guide thromboprophylactic treatment decisions. The well-known CHADS(2) scoring system incorporates risk factors such as congestive heart failure, hypertension, age 75 years or older, diabetes mellitus, and previous stroke or transient ischemic attack. Recently, a novel risk stratification model, CHA(2)DS(2)-VASc, has entered the literature and international guidelines, prompting further review of newly added risk factors-age 65-74 years, presence of vascular disease, and female sex-and the increased allotment of 2 points (vs 1 point in CHADS(2)) for age 75 years or older. The rationale for CHA(2)DS(2)-VASc, as put forth by its authors, is that other risk assessment models omit important risk factors, have low predictive ability, and categorize too many patients as intermediate risk, leaving the choice of anticoagulant or antiplatelet therapy to the discretion of the clinician. Although CHA(2)DS(2)-VASc readily identifies those patients truly at low risk, it classifies more patients as high risk who would then receive anticoagulation therapy. Therefore, implementation of this risk schema warrants further evaluation, especially when weighing the risk for bleeding and the risk for stroke. This critical review provides practitioners with an understanding of the literature that prompted the inclusion of these new risk factors and increased point allocations, compares and contrasts the risk schemas, and reviews national and international guidelines, thereby equipping the health care provider with the knowledge to aid clinical decision-making.