Stroke News from the European Society of Cardiology Congress 2011 in Paris
Apixaban Versus Warfarin for Stroke Prevention in Patients With Atrial Fibrillation
A large-scale, randomized, double-blind study has found that apixaban is superior to warfarin for preventing stroke and systemic embolism in patients with atrial fibrillation. Moreover, apixaban resulted in substantially less bleeding and lower mortality. The benefits of apixaban are consistent irrespective of how well warfarin was used at different centers, as measured by “time in therapeutic range,” according to researchers.
The ARISTOTLE trial included 18,201 patients at 1,034 clinical sites in 39 countries who received apixaban (5 mg twice daily) or warfarin for an average of 1.8 years. Results were also published in the September 15 New England Journal of Medicine.
“These are important findings, because they show that when compared to warfarin, itself a very effective treatment to prevent stroke, apixaban resulted in an additional 21% relative reduction in stroke and systemic embolism. It also resulted in a 31% relative reduction in major bleeding, as well as an 11% relative reduction in overall mortality,” said Christopher B. Granger, MD, Professor of Medicine at Duke University in Durham, North Carolina. In addition, hemorrhagic stroke was reduced by about 50%.
Lars Wallentin, MD, PhD, Professor of Cardiology and Director of the Uppsala Clinical Research Center in Sweden, noted that these benefits are for a drug that has major practical advantages compared with warfarin in that it does not require monitoring and has few interactions with other medications or food. Apixaban was better tolerated than warfarin, with fewer discontinuations. Dr. Wallentin added that “the benefits of reducing stroke and lower rates of bleeding were consistent across all major subgroups and despite the heterogeneity that exists in the quality of warfarin use across the world.”
According to John Alexander, MD, Associate Professor of Medicine, Cardiology at Duke University and study coauthor, “Apixaban prevented six patients from having a stroke, 15 patients from having major bleeding, and eight patients from dying. The predominant effect on stroke prevention was for hemorrhagic stroke. Apixaban prevented four patients from having hemorrhagic stroke and two patients from having an ischemic or uncertain type of stroke.”
Warfarin, a vitamin K antagonist, has a well documented ability to prevent blood clots. Previous studies have shown that long-term use of warfarin in patients with atrial fibrillation and other stroke risk factors can reduce stroke by up to 70%. However, only about half of patients who could benefit from warfarin actually do. Patients on warfarin must have regular blood tests to monitor and adjust the dose and avoid certain foods and medications that interfere with warfarin’s effect. Warfarin also increases bleeding risk, including intracranial hemorrhage.
Apixaban, an oral direct factor Xa inhibitor, showed promise last year when trial findings showed that apixaban patients were 54% less likely to have a stroke or blood clot than those who took aspirin. Apixaban and aspirin showed similar risks of major bleeding.
“Our study indicates that treatment with apixaban is more effective than warfarin in preventing stroke without the need for anticoagulation monitoring,” said Dr. Wallentin, who added that the results also show that apixaban is safer than warfarin. “Our findings show that a single dose of apixaban accomplishes the same stroke prevention goal as adjusted-dose warfarin with a substantially lower risk of all types of bleeding across different ages, and with lower rates of discontinuation,” he commented.
An Upgraded Risk Measurement Tool for Heart Attacks and Strokes
Researchers are hopeful that the imminent launch of an update to the HeartScore application will reduce the number of heart attack and stroke incidents in Europe. HeartScore was first developed by the European Society of Cardiology (ESC) in 2004, and it helps clinicians rapidly estimate the risk of cardiovascular disease in individual patients using age, gender, basic health indicators, and lifestyle factors.
The results from the model are then used to shape intervention and advice regimes aimed at lowering cardiovascular disease risk. Following feedback, HeartScore has been updated to incorporate a number of new features that will enhance its value as part of cardiovascular disease prevention strategies.
According to Ian Graham, MD, Chair of the Prevention Implementation Committee of the ESC’s European Association of Cardiovascular Prevention and Rehabilitation (EACPR) and project leader for HeartScore, “This important update continues our work to develop a practical tool for accessible cardiovascular disease risk estimation. Clinicians have told us that, above all, they want accurate, fast, and simple information that is relevant to them and their patients. I am confident that this new release of HeartScore will meet those needs and benefit patients everywhere.”