Only 33% high risk patients received oral anticoagulation (OCA) with warfarin at diagnosis. Some features were found to be significant independent risk factors for OCA: age (older than 75 vs 65-74 years; odds ratio =0.32; 95% confidence interval, 0.18-0.59), and prior stroke (odds ratio =2.02; 95% confidence interval, 1.16-3.55).