ORLANDO, Fla.—Suboptimal oral anticoagulant therapy (OAC), which varies in event rates across institutions, indicates the need for improved management of patients with atrial fibrillation (AF) to prevent stroke in clinical practice, according to a poster study presented on Sunday at the 58th annual American College of Cardiology (ACC) scientific sessions.
Isla M. Ogilvie, PhD, from BioMedCom Consultants in Montreal and colleagues from the City Hospital in Birmingham, England, identified 98 (1997-2008) on current treatment practice for stroke prevention in patients with AF, and a further 53 on clinical event rates (stroke, transient ischemic attack [TIA], embolism and bleeding). Of these, 29 studies contained treatment data for AF patients with prior stroke or TIA and these were used for the primary analysis.
According to treatment guidelines, patients with prior stroke or TIA should all receive OAC therapy.
The researchers found that patients with prior stroke or TIA were under-treated with OAC therapy (a treatment level of less than 80 percent of eligible patients) in all but one of the 29 studies. Indeed, 21 of 29 studies reported OAC treatment levels below 60 percent. Only eight of the 29 studies accounted for AF patients in their population who had contraindications to OAC therapy.
Ogilvie and colleagues found that subjects with CHADS2 score of two or more were sub-optimally treated; eight of the nine studies reported treatment levels below 80 percent. They also found that studies (21 from 54) that used other stroke risk stratification schemes to designate patients high risk differ in the criteria they use to delineate stroke risk; as such, direct comparison is not possible.
In general, patients at a high risk of stroke were under treated (range 22.8 to 81.9 percent), according to the researchers. Nearly three quarters of the studies analyzed reported a treatment level of under 60 percent of eligible patients.
The investigators also observed little difference in major bleeding rates between provider settings; however, the "definition of major bleeding differed from study to study limiting the validity of the comparison."
Ogilvie and colleagues concluded that the overall under treatment of high risk AF patients with warfarin in clinical practice, couple with increased rates of ischemic stroke in real life clinical settings when AF patients are treated, reflecting "the need for improvements in our provision of thromboprophylaxis in AF."
"There is an evident need for OAC drugs with wide therapeutic range, as well as a safe bleeding profile," the authors wrote.