Risk factors for stroke and other embolic events in patients with nonrheumatic atrial fibrillation.

Factors associated with stroke and other cardiac embolic events in subjects with nonrheumatic atrial fibrillation were examined in a retrospective study of 91 patients from a teaching hospital clinic. There were 28 first strokes during 355 person-years of follow-up (7.9 per 100 person-years). Patients who had experienced one or more previous events were approximately 2.3 times more likely to have a subsequent event (hazard ratio 2.3, 95% confidence interval 1.5-3.4) than patients who had experienced no events. A univariate analysis of factors associated with a first stroke of any cause or other embolic event showed that age of greater than 75 years (hazard ratio 2.5) and systolic blood pressure of greater than 160 mm Hg (hazard ratio 6.4) were significant factors. After adjusting for the effect of age and systolic blood pressure, previous events still carried an increased risk for subsequent events. Subject with nonrheumatic atrial fibrillation who have had one or more embolic events are at high risk of further emboli. They require special consideration when treatment is being planned.