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In 2012, stroke was identified as the fourth leading cause of death in the United States, attributing to 1 out of 18 deaths per year.1 In 2010 alone, stroke accounted for $73.7 million in medical related costs and disability.2,3 Atrial fibrillation is an independent risk factor for stroke and a prevalent arrhythmia (affecting 1 in 4 individuals). The risk for stroke in patients with atrial fibrillation varies considerably given the patient’s past medical history and co-morbid conditions.4 Pharmacotherapy management with oral anticoagulants is a key component in the primary prevention of stroke, particularly in high-risk patients with atrial fibrillation. According to the 2012 CHEST guidelines, dabigatran, a direct oral thrombin inhibitor, and warfarin are recommended in high-risk patients with atrial fibrillation with consideration given to dabigatran as the recommended option. Since the guidelines were published, two new oral direct factor Xa inhibitor anticoagulants were approved for prevention of stroke in patients with atrial fibrillation. While the trials on the new anticoagulants are promising with similar or superior efficacy and less or similar bleeding risk as warfarin, post-marketing data surrounding the usage of these newer anticoagulants are raising concerns about long term risk and major bleeding, reversal strategies for the anticoagulant effect, and the associated cost-effectiveness.4 

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Apixaban (Eliquis®) is the most recently approved direct factor Xa inhibitor anticoagulant (December 2012) for the prevention of stroke and systemic embolism in patients with non-valvular atrial fibrillation.5 Its approval was based on the results of the ARISTOLE (apixaban versus warfarin) and AVERROES (apixaban versus aspirin) studies. In these multinational, double-blind phase III clinical trials apixaban was found to be superior to dose-adjusted warfarin and low-dose aspirin for the prevention of stroke and systemic embolism in patients with atrial fibrillation. All-cause mortality and risk for major bleeding (defined as overt bleeding accompanied by at least one of the following: a decrease in hemoglobin, transfusion of ≥ 2 units, or internal hemorrhaging of any kind) with apixaban was similar to low-dose aspirin, but significantly lower than dose-adjusted warfarin.6,7 The AVERROES study was terminated early after a mean follow-up of 1.1 years due to superiority of apixaban over aspirin. While no difference in major bleeding was witnessed, the potential for such differences with longer usage cannot be excluded.6 The ARISTOLE study evaluated two doses of apixaban, 2.5 mg twice-daily or 5mg twice-daily. The lower dosage was given in order to prevent adverse events and was found to be an effective dose in patients with at least 2 of the following characteristics: a serum creatinine (Scr) of ≥ 1.5 mg/dL, a weight of ≤ 60 kg, or were ≥ 80 years of age.7 The data on the lower dose was used to drive apixaban dosing recommendations.3 Similar evidence is lacking with some of the alternate dosages for the other newer anticoagulants.

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Data correlating the impact of the newer anticoagulants with stroke risk stratification models commonly used in ...

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