Is atrial flutter a risk factor for stroke?

Large prospective, randomized, controlled trials have demonstrated the efficacy of anticoagulation for the prevention of cardioembolic stroke in atrial fibrillation. Anticoagulation with warfarin is associated with a 70% relative risk reduction in thromboembolic events for certain high risk groups and this can be accomplished without a substantive risk of major bleeding (1–3). Whether chronic atrial flutter carries a similar risk to atrial fibrillation for cardioembolic stroke and whether anticoagulation reduces that risk remain controversial. To our knowledge, no randomized trials of anticoagulation for stroke prevention in chronic atrial flutter have been performed and uniform recommendations regarding anticoagulation in atrial flutter have not been established (4). Our knowledge regarding cardioembolic stroke in this area has been derived in part from the large prospective, randomized trials of atrial fibrillation that have included patients with atrial flutter, observational studies of the prevalence of left atrial thrombus in atrial flutter, mechanistic studies that have examined the development of left atrial mechanical stunning and thrombus formation following the cardioversion of atrial flutter and various case reports and retrospective studies of embolic stroke that have complicated the cardioversion of atrial flutter to sinus rhythm (1–3,5–17).