<International Circulation>: Atrial fibrillation is a common cause of cardioembolic stroke， particularly among the elderly. While warfarin is an effective therapy for the prevention of stroke in atrial fibrillation， there is an underutilization of warfarin in patients who might benefit from this therapy. What are the reasons for the underutilization of warfarin?

Prof. Diener: One reason is that it is difficult to use because monitoring is a nuisance. Another reason for this underutilization is that many physicians and patients are afraid of the bleeding risk. They have no real perception of what the benefit is compared to the bleeding risk.