The preliminary results of the AVERROES (Apixaban versus acetylsalicylic acid to reduce the risk of stroke in patients with atrial fibrillation) trial were presented by Stefan Hohnloser, J W Goethe University, Frankfurt, Germany, at the annual Europe AF meeting in London, UK.
Apixaban is an oral, selective, direct factor Xa inhibitor with 12-hour half-life, multiple excretion pathways (25% renal) and no routine coagulation monitoring. The ADVANCE 1-3 trials showed that apixaban is effective and safe for venous thromboembolism prevention in orthopaedic surgery.
Vitamin K antagonist therapy is effective against stroke, but it is considered unsuitable for up to 50% of patients as it is difficult to control international normalised ratio and bleeding on vitamin K antagonist. There is a need for an effective, safe and easy-to-use antithrombotic therapy for AF patients, unsuitable for vitamin K antagonist.
The double-blind, randomised trial included 5,600 patients in 522 centres in 36 countries taking apixaban 5mg bid with 2.5 mg bid in selected patients or acetylsalicylic acid (81–324mg/d). Primary outcome was stroke or systemic embolic event.
The Data Monitoring Committee recommended early study termination at first analysis of efficacy on 28 May 2010. Ninety four per cent of patients received apixaban 5mg bid and 91% patients received acetylsalicylic acid ≤162mg daily with median follow-up to one year. Total serious adverse events for apixaban were 1,040 and 1,230 for acetylsalicylic acid.
One thousand patients were treated with apixaban for one year, instead of acetylsalicylic acid. The study expects to prevent 18 strokes, mostly larger, 10 deaths and 31 cardiovascular hospitalisations at a cost of two major bleeds.
Apixaban is well tolerated compared to acetylsalicylic acid, without evidence of liver toxicity, Hohnloser said. For atrial fibrillation patients unsuitable for vitamin K antagonist, apixaban has a favourable risk benefit profile, the study concluded.