Apixaban vs Aspirin According to CHA2DS2-VASc Score in Subclinical Atrial Fibrillation Insights From ARTESiA

BACKGROUND: ARTESiA (Apixaban for the Reduction of Thrombo-Embolism in Patients With Device-Detected Sub-Clinical Atrial Fibrillation) demonstrated that apixaban, compared with aspirin, significantly reduced stroke and systemic embolism (SE) but increased major bleeding in patients with subclinical atrial fibrillation. OBJECTIVES: To help inform decision making, the authors 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 1,578 (39.4%) patients, 4 in 1,349 (33.6%), and >4 in 1,085 (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 (95% CI: 0.43-2.12) strokes/SE per 100 patient-years and caused 0.68 (95% CI: -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 (95% CI: -0.38 to 0.62) strokes/SE per 100 patient-years and caused 0.33 (95% CI: -0.27 to 0.92) major bleeds. For patients with CHA₂DS₂-VASc =4, apixaban prevented 0.32 (95% CI: -0.16 to 0.79) strokes/SE per 100 patient-years and caused 0.28 (95% CI: -0.30 to 0.86) major bleeds. CONCLUSIONS: One in 4 patients in ARTESiA with subclinical atrial fibrillation 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. (Apixaban for the Reduction of Thrombo-Embolism in Patients With Device-Detected Sub-Clinical Atrial Fibrillation; NCT01938248).