The ATRIA study has followed outcomes in a large group of more than 13,500 patients with atrial fibrillation and has found that the risk of stroke has declined over the past two decades.
Researchers explored outcomes of four strategies: anticoagulate with warfarin; anticoagulate with a new, "safer" agent, using dabigatran (another anticoagulant) as the prototype; treat with aspirin; and no antithrombotic therapy.
"We used a standard computer program to build the model, analyze results and perform sensitivity analyses," Eckman says. "Our base case involved a hypothetical 69-year-old man with non-valvular atrial fibrillation who had no contraindications to warfarin therapy."
Researchers found that warfarin is preferred above a stroke rate of 1.7 percent per year, corresponding to a CHADS2 score of 0 using the historically higher rates of stroke of the older CHADS2 derivation cohort.
Eckman continues, "Using more contemporary and lower estimates of stroke risk raises the threshold for use of warfarin to a CHADS2 score of greater than or equal to 2 (moderate to high risk). However, anticoagulation with a new, 'safer' agent leads to a lowering of the threshold for anticoagulation to a stroke rate of 0.9 percent per year.
"Our analysis suggests that the 'tipping point,' the threshold of ischemic stroke risk below which anticoagulant therapy should be withheld and above which anticoagulant therapy should be prescribed, has changed," he says. "
|Contact: Katie Pence|
University of Cincinnati Academic Health Center