The search for paroxysmal atrial fibrillation in cryptogenic stroke: leave no stone unturned.

Atrial fibrillation (AF), a well-established cause of ischemic stroke, is found in up to 25% of first strokes.(1,2) Most patients with stroke from AF will benefit from anticoagulation for secondary stroke prevention, so finding AF as a cause of ischemic stroke is critical. Many patients with AF have paroxysmal AF (PAF), in which periods of normal sinus rhythm alternate with sometimes brief episodes of AF. Conventional monitoring for AF in the hospital or for a small number of days as an outpatient may therefore miss the diagnosis of PAF. Although most of the data to support anticoagulation for stroke patients with AF come from patients with continuous AF, PAF has a similar risk of stroke when compared to continuous AF(3,4) and there appears to be a similar benefit of anticoagulation in reducing the risk of stroke in patients with PAF.(3.)