Anticoagulation therapy for stroke prevention in atrial fibrillation: how well do randomized trials translate into clinical practice?

Context: Warfarin has been shown to be highly efficacious for preventing thromboembolism in atrial fibrillation in randomized trials, but its effectiveness and safety in clinical practice is less clear.

Objective: To evaluate the effect of warfarin on risk of thromboembolism, hemorrhage, and death in atrial fibrillation within a usual care setting.

Design: Cohort study assembled between July 1, 1996, and December 31, 1997, and followed up through August 31, 1999.

Factor V Leiden and risk of ischemic stroke in nonvalvular atrial fibrillation: the AnTicoagulation and Risk Factors in Atrial Fibrillation (ATRIA) Study.

Background: Atrial fibrillation is a major cause of cardioembolic stroke. Since atrial and venous pressures are similar, genetic variants that promote venous thromboembolism may increase the risk of atrial thrombi and subsequent stroke in atrial fibrillation.

Methods: We conducted a nested case-control study of the association between the presence of factor V Leiden polymorphism and incident ischemic stroke within a prospective cohort of 13,559 adult patients with diagnosed nonvalvular atrial fibrillation between July 1, 1996 and December 31, 1997.