The rate of primary outcomes was significantly reduced in patients receiving oral anticoagulation (8%) compared to those in control group (17% per year). The difference was even more pronounced in the reduction in risk of stroke alone. Oral anticoagulation was found to be more effective than aspirin in preventing the occurrence of a primary event (p=0.008). Results of aspirin vs. placebo arms of both groups were combined. Patients assigned to aspirin had a lower risk of a primary outcome event and of stroke alone but neither effects were statistically significant.