BACKGROUND- Atrial fibrillation is responsible for approximately one in seven strokes in patients of all ages and for one in four strokes in patients aged >80 years. Warfarin reduces stroke risk by approximately 70% and aspirin by 20%.
REVIEW SUMMARY- Although the average annual risk of stroke is approximately 5%, there is substantial risk heterogeneity within the population of patients with atrial fibrillation. Risk stratification on the basis of demographic, clinical, and echocardiographic features identifies populations with annual risk of stroke ranging from >7%, clearly warranting warfarin anticoagulation, to <1%, at which the risks and disutility of antithrombotic therapy offset its benefits. Analyses of risk factors consistently show that a previous transient ischemic attack or stroke is a potent predictor of subsequent thromboembolism. The effects of advancing age, left ventricular dysfunction, diabetes, coronary disease, and hypertension are less uniformly established. Transthoracic echocardiography has an ancillary role in current stratification schemes, whereas those of transesophageal echocardiography and hemostatic studies have not yet been established. Predictors of thromboembolism, such as advanced age, unfortunately coincide with risk factors for bleeding on warfarin in atrial fibrillation patients. Audits of patient management have shown that many patients with atrial fibrillation are not receiving preventive treatments. This is particularly true among the elderly.
CONCLUSION- Considerable progress has been made over the past decade in our ability to prevent strokes among patients with atrial fibrillation. Wider application of these advances could prevent many thousands of additional strokes each year. Better predictors, safer antithrombotic programs, and other approaches are still needed.