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AVERROES: Apixaban reduced risk for stroke in patients with AF
Connolly S. Session 708005–708006.
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European Society of Cardiology Congress 2010
Results from a new study have shown that patients with atrial fibrillation at risk for stroke and unsuitable for vitamin K antagonist therapy given apixaban had a reduced risk for stroke and systemic embolism without a significantly increased risk for major hemorrhage.
Researchers for the Apixaban Versus Acetylsalicylic Acid to Reduce the Risk of Stroke (AVERROES) study compared apixaban (Pfizer/Bristol-Myers Squibb) to aspirin in patients with documented AF who had at least one risk factor for stroke and were unsuitable for vitamin K antagonists. The patients (n=5,600; mean age, 70 years) were randomly assigned 1:1 to receive either 5 mg twice daily of apixaban — 2.5 mg twice daily in selected patients — or between 81 and 324 mg per day of aspirin.
According to study results, the annual rate of stroke or systemic embolism was notably lower in the apixaban group vs. aspirin (1.7% vs. 4%; HR=0.43; 95% CI, 0.30-0.62). The annual rate of major hemorrhage was slightly higher in the apixaban group (1.5% vs. 1.2%; HR=1.26; 95% CI, 0.79-2.00), whereas the rate of hemorrhagic stroke was 0.2% per year in both treatment groups (HR=1.15; 95% CI, 0.42-3.17).
Stuart Connolly, MD,director, division of cardiology, department of medicine, McMaster University, Ontario, Canada, and study researcher, said in his presentation that by using apixaban instead of aspirin in 1,000 patients, physicians can expect to prevent 18 strokes, 10 deaths and 31 CV hospitalizations at the cost of two major bleeds.
AVERROES is a landmark study with impressing design, protocolled statistics, conduction and results. The results emphasize the well-known pathophysiological basis for the thrombotic origin in the left atrial appendage, being a typical coagulation thrombus similar to venous thrombosis with activation of the coagulation system via factor Xa and formation of a fibrin-rich product, and with only limited activation of platelets. However, the clinically important consequence of stroke is based on embolic phenomenon to an intracerebral artery.
The results from AVERROES will obviously have impact on guidelines for antithrombotic treatment in patients with AF, and the use of acetylsalicylic acid will probably be drastically reduced in these patients. The patients being unsuitable for vitamin K antagonist therapy should be clearly defined, possibly a challenging task. With two daily oral doses of apixaban, compliance will be a challenge, and surveillance studies (phase IV) should be undertaken.
– Harald Arnesen, MD
Center for Clinical Research, Oslo University Hospital Ullevål, Oslo
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