Apixaban vs. Aspirin for Secondary Stroke Prevention in Atrial Fibrillation
This new oral anticoagulant drug significantly reduced the rate of thromboembolism without increasing the rate of intracranial hemorrhage.
Anticoagulation with warfarin decreases the risk for stroke from atrial fibrillation (AF) significantly more than antiplatelet therapy. However, one third of patients with AF and prior stroke or transient ischemic attack (TIA) who are eligible for warfarin instead receive antiplatelet therapy, often because of concerns about bleeding. For these patients, new drugs are clearly needed that are as effective as warfarin but as safe as aspirin.
To address this need, investigators have performed an industry-sponsored, prespecified subgroup analysis of patients with prior stroke or TIA enrolled in the AVERROES trial. AVERROES compared outcomes with 5 mg twice daily of apixaban (a factor Xa inhibitor currently available in Europe) and with 81 to 324 mg of aspirin daily in 5599 patients with AF and at least one stroke risk factor who were considered ineligible for warfarin therapy. Exclusion criteria included high risk for bleeding or having experienced serious bleeding within the previous 6 months. Mean follow-up was 1.1 years. The current subgroup analysis included the 764 participants with a prior stroke or TIA.
In the subgroup, the cumulative annual risk for ischemic stroke was 7.46% with aspirin versus 2.12% with apixaban (hazard ratio, 0.33). The rate of intracranial hemorrhage was 1.56% with aspirin versus 1.17% with apixaban. Major bleeding occurred more often with apixaban (4.10%) than with aspirin (2.89%).
Comment: Compared with aspirin, apixaban dramatically reduced the risk for recurrent ischemic stroke in patients with AF, with no apparent increase in the risk for intracranial hemorrhage. This finding reflects the performance of these drugs in the setting of a clinical trial, which involves patients who may be less sick and less frail than patients in the community. Nevertheless, results such as these will make it increasingly inappropriate to prescribe antiplatelet therapy alone to patients with AF and prior stroke or TIA who have no firm contraindications to anticoagulation.
Hooman Kamel, MD
Published in Journal Watch Neurology March 6, 2012
Diener H-C et al. Apixaban versus aspirin in patients with atrial fibrillation and previous stroke or transient ischaemic attack: A predefined subgroup analysis from AVERROES, a randomised trial. Lancet Neurol 2012 Mar; 11:225. [Medline ® Abstract]