The CHA2DS2-VASc score identifies those patients with atrial fibrillation and a CHADS2 score of 1 who are unlikely to benefit from oral anticoagulant therapy.

AIMS The CHA(2)DS(2)-VASc score is a modification of the CHADS(2) score that aims to improve stroke risk prediction in patients with atrial fibrillation (AF) by adding three risk factors: age 65-74, female sex, and history of vascular disease. Whereas previous evaluations of the CHA(2)DS(2)-VASc score included all AF patients, the aim of this analysis was to evaluate its discriminative ability only in those patients for whom recommendations on antithrombotic treatment are uncertain (i.e. CHADS(2) score of 1). METHODS AND RESULTS We selected all patients with a CHADS(2) score of 1 from the AVERROES and ACTIVE trials who were treated with acetylsalicylic acid with or without clopidogrel and calculated the incidences of ischaemic or unspecified stroke or systemic embolus (SSE) according to their CHA(2)DS(2)-VASc score. Of 4670 patients with a baseline CHADS(2) score of 1, 26% had a CHA(2)DS(2)-VASc score of 1 and 74% had a score of ≥ 2. After 11 414 patient-years of follow-up, the annual incidence of SSE was 0.9% (95% CI: 0.6-1.3) and 2.1% (95% CI: 1.8-2.5) for patients with a CHA(2)DS(2)-VASc score of 1 and ≥ 2, respectively. The c-statistic of the CHA(2)DS(2)-VASc score was 0.587 (95% CI: 0.550-0.624). Age 65 to <75 years was the strongest of the three new risk factors in the CHA(2)DS(2)-VASc score. CONCLUSION The CHA(2)DS(2)-VASc score reclassifies 26% of patients with a CHADS(2) score of 1 to a low annual risk of SSE of 1%. This risk seems low enough to consider withholding anticoagulant treatment.