Apixaban versus Aspirin According to CHA2DS2-VASc Score in Subclinical Atrial Fibrillation: Insights from ARTESiA

Background ARTESiA demonstrated that apixaban, compared with aspirin, significantly reduced stroke and systemic embolism (SE) but increased major bleeding in patients with subclinical atrial fibrillation (SCAF). Objectives To help inform decision making, we evaluated the efficacy and safety of apixaban according to baseline CHA2DS2-VASc score. Methods We performed a subgroup analysis according to baseline CHA2DS2-VASc score and assessed both the relative and absolute differences in stroke/SE and major bleeding. Results Baseline CHA2DS2-VASc scores were <4 in 1578 (39.4%) patients, 4 in 1349 (33.6%), and >4 in 1085 (27.0%). For patients with CHA2DS2-VASc >4, the rate of stroke was 0.98%/year with apixaban and 2.25%/year with aspirin; compared with aspirin, apixaban prevented 1.28 (0.43 to 2.12) strokes/SE per 100 patient-years and caused 0.68 (-0.23 to 1.57) major bleeds. For CHA2DS2-VASc <4, the stroke/SE rate was 0.85%/year with apixaban and 0.97%/year with aspirin. Apixaban prevented 0.12 (-0.38 to 0.62) strokes/SE per 100 patient-years and caused 0.33 (-0.27 to 0.92) major bleeds. For patients with CHA2DS2-VASc =4, apixaban prevented 0.32 (-0.16 to 0.79) strokes/SE per 100 patient-years and caused 0.28 (-0.30 to 0.86) major bleeds. Conclusion One in 4 patients in ARTESiA with SCAF had a CHA2DS2-VASc score >4 and a stroke/SE risk of 2.2% per year. For these patients, the benefits of treatment with apixaban in preventing stroke/SE are greater than the risks. The opposite is true for patients with CHA2DS2-VASc score <4. A substantial intermediate group (CHA2DS2-VASc =4) exists in which patient preferences will inform treatment decisions.