New Stroke Drug Apixaban Effective, Study Stopped
A new drug, apixaban, has provided impressive evidence in the prevention of stroke, enough to prompt investigators to stop the AVERROES study. The new stroke drug was being tested to prevent stroke in patients with atrial fibrillation who cannot take warfarin.
Development of apixaban is a collaborative effort between Bristol-Myers Squibb and Pfizer. The drug is a new type of anticoagulant known as a Factor Xa inhibitor that blocks the coagulation system without the need for monitoring required in other treatments, such as warfarin.
Apixaban Stroke Study
The AVERROES study involved 5,600 patients with atrial fibrillation who were at risk for stroke but also unable to take any vitamin K antagonists such as warfarin. The participants were randomly assigned to receive either apixaban or aspirin in the double-blind study.
The data monitoring committee of the study found a greater than 50 percent reduction in risk for stroke and systemic embolism along with a modest increase in major hemorrhage, which was deemed to be not statistically significant. Principle investigator Dr. Stuart J. Connolly, chairman of the steering committee and a professor of medicine at the Michael G. DeGroote School of Medicine at McMaster University, called the findings “truly impressive.”
Connolly noted that “it appears that apixaban will be an excellent treatment for the many patients with atrial fibrillation who are unsuitable for warfarin. These findings will reduce the burden of stroke in society.”
According to the American Heart Association’s “Heart Disease & Stroke Statistics, 2010 Update-at-a-Glance” report, 795,000 new and recurrent strokes occurred in 2006, the year for which the AHA has the most recent statistics. Women are more likely than men to experience a stroke (425,000 vs 370,000) and also more likely to die of stroke. The AHA noted that there were 137,100 deaths attributed to stroke in 2006, with 82,600 deaths among women and 54,500 among men.
An estimated 15 percent of strokes are a result of untreated atrial fibrillation, a condition in which the two upper chambers of the heart (atria) fibrillate instead of contracting completely. About 2 million Americans experience atrial fibrillation, and it is the most common type of irregular heartbeat. Atrial fibrillation increases the risk of stroke by approximately fivefold.
What the New Study Means
Many patients at risk for stroke and with atrial fibrillation cannot take warfarin, and so the only alternative is aspirin, which is not very effective. The results of this interrupted study indicate that the new stroke drug apixaban may be a suitable treatment for this population of patients. Apixaban has shown promise in earlier studies in patients who have deep vein thrombosis and in those who have undergone orthopedic surgery or experienced acute coronary syndrome. It had not been studied in patients with atrial fibrillation previously.
American Heart Association
American Stroke Association