Apixaban in Patients With Atrial Fibrillation
Is apixaban superior to aspirin for stroke prevention in atrial fibrillation (AF)?
In this double-blind study, 5,599 patients (mean age 70 years) with AF and ≥1 risk factor for stroke who were unsuitable candidates for treatment with warfarin were randomly assigned to receive apixaban, 5 mg twice daily (n = 2,808), or aspirin, 81-325 mg/day (n = 2,791). The patients were followed for a mean of 13 months. The primary outcomes were stroke/systemic embolism and major bleeding.
The incidence of stroke/embolism was significantly lower in the apixaban group (1.6%/year) than in the aspirin group (3.7%/year). The 3.5%/year mortality rate in the apixaban group did not differ significantly from the 4.4%/year mortality rate in the aspirin group. The annual incidence of major bleeding also did not differ significantly between the apixaban (1.4%) and aspirin (1.2%) groups. First hospitalizations for a cardiovascular cause were significantly less common with apixaban (12.6%/year) than with aspirin (15.9%).
Compared to aspirin, apixaban reduces the risk of stroke/embolism by 55% without increasing the risk of bleeding complications.
Apixaban, an inhibitor of factor Xa, previously has been shown to be as effective as warfarin and enoxaparin for preventing thrombophlebitis after knee replacement. The present study is the first to evaluate the efficacy of apixaban in patients with AF who are not suitable candidates for warfarin, either because of patient refusal or medical reasons. Another alternative to warfarin in patients with AF is the recently-approved direct thrombin inhibitor, dabigatran. A potential advantage of apixaban is that it is reversible, whereas dabigatran has no antidote. The relative efficacy and safety of apixaban versus dabigatran for stroke prevention in AF remain to be determined.
Keywords: Incidence, Stroke, Thrombin, Thrombophlebitis, Benzimidazoles, Risk Factors, Pyrazoles, Embolism, Pyridones
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