Benefit of Anticoagulation Unlikely in Patients With Atrial Fibrillation and a CHA2DS2-VASc Score of 1 | Journal Scan
What is the risk of stroke in atrial fibrillation (AF) patients with a CHA2DS2-VASc stroke risk score of 1?
Using Swedish nationwide health registries, 140,420 patients with nonvalvular AF, but no anticoagulant therapy between 2005 and 2010, were examined. All patients had a CHA2DS2-VASc score of 1. “Stroke” was broadly defined to include ischemic stroke, unspecified stroke, transient ischemic attack, and pulmonary embolism.
By including a broad definition of “stroke,” the annual risk was 44% higher than for traditional definitions of stroke in this cohort. For patients with a CHA2DS2-VASc score of 1, annual stroke rate varied between 0.5-0.9%, depending on the definition of “stroke.” For women with a CHA2DS2-VASc score of 1, annual “stroke” rates varied between 0.1% and 0.2%, whereas men with a CHA2DS2-VASc score of 1 had an annual “stroke” rate of 0.5% and 0.7%. Among the entire national cohort of AF patients, 46.2% of men and 22.5% of women with a CHA2DS2-VASc score of 1 had warfarin use at baseline.
The authors concluded that the risk of ischemic stroke in AF patients with a CHA2DS2-VASc score of 1 appears to be lower than previously reported.
Using a national registry of AF patients, the authors demonstrated a low annual risk of stroke in patients with a CHA2DS2-VASc score of 1 who were not treated with warfarin. However, during the same study period, 46.2% of all CHA2DS2-VASc patients in Sweden were treated with warfarin, raising the concern about selection bias in the untreated cohort. Of particular interest are the various definitions of “stroke” assessed in this study, including use of transient ischemic attack and pulmonary embolism. Even when the looser definition of stroke was assessed, risk in this cohort remained <1% per year. While no formal bleeding risk was assessed in this same study, there are legitimate concerns about the balance between stroke and bleeding risk when anticoagulating AF patients with a CHA2DS2-VASc score of 1. Clinicians should recall that the European guidelines favor anticoagulation for men (but not for women) with a CHA2DS2-VASc score of 1, which is justified based on these study results.
Keywords: Anticoagulants, Atrial Fibrillation, Ischemic Attack, Transient, Pulmonary Embolism, Risk, Stroke, Warfarin
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