Apixaban superior to aspirin in reducing stroke and systemic embolism in patients with atrial fibrillation


The AVERROES (Apixaban versus acetylsalicylic acid to prevent strokes) study demonstrated that, for patients with atrial fibrillation (AF) who were expected or demonstrated to be unsuitable for a vitamin K antagonist (VKA) therapy such as warfarin, apixaban was statistically superior to aspirin in reducing the composite of stroke or systemic embolism, without a significant increase in major bleeding, fatal bleeding or intracranial bleeding. Importantly, there were no significant differences in the risk of hemorrhagic stroke between apixaban and aspirin.

The study results also showed that apixaban demonstrated superiority for its secondary efficacy endpoint in reducing the composite of stroke, systemic embolism, myocardial infarction or vascular death for patients with AF when compared with aspirin. Conducted in 36 countries, the study was coordinated by the Population Health Research Institute (PHRI) at McMaster University and at Hamilton Health Sciences in Canada.

Aspirin has remained a treatment option in patients for whom warfarin or other VKAs have been demonstrated or predicted to carry unacceptable bleeding risks. This study was designed to address whether a more favorable option might exist for this patient population.

Apixaban is an investigational, oral, highly selective Factor Xa inhibitor, part of a class of agents being studied for their potential to prevent and treat blood clots in the veins and arteries. Preliminary results of AVERROES were first presented in August 2010, at the European Society of Cardiology annual meeting in Stockholm, Sweden, at the annual Europe AF meeting in London, UK and recently, at the International Stroke Conference in Los Angeles, USA.

“The risk of stroke or systemic embolism is of great concern for patients with atrial fibrillation, especially because AF-related strokes can be particularly devastating,” said Stuart Connolly, professor of medicine at McMaster University in Hamilton, Canada, and lead investigator of the study. “We are encouraged by the AVERROES data, which demonstrated that apixaban is more effective than aspirin without a significantly increased risk of major bleeding. Given the significant number of patients who are not eligible for treatment with vitamin K antagonists, it is especially important to have potential new treatment options that are both safe and effective.”

About the apixaban clinical trials programme

Apixaban is being investigated within the EXPANSE clinical trials programme, which is projected to incorporate nearly 60,000 patients worldwide across multiple indications and patient populations and includes a total of nine completed or ongoing, randomised, double-blind phase III trials, including AVERROES.

The AVERROES trial is one of two phase III clinical trials exploring the efficacy and safety of apixaban for stroke prevention in patients with AF. The ongoing ARISTOTLE trial is investigating apixaban compared with warfarin in 18,206 patients with AF. Data from this trial are expected to be presented at a major medical meeting later this year.

In addition to prevention of stroke and other thromboembolic events in patients with atrial fibrillation, apixaban is in phase III trials studying the prevention and treatment of venous thromboembolism.