Subclinical Atrial Fibrillation and the Risk of Stroke

A cohort of 2580 patients with pacemakers or defibrillators were monitored for 3 months to detect subclinical atrial tachyarrhythmias. Patients with subclinical atrial tachyarrhythmias had a significantly increased risk of subsequent ischemic stroke. Atrial fibrillation may be asymptomatic and consequently subclinical. 1 , 2 Epidemiologic studies indicate that many patients with atrial fibrillation on screening electrocardiograms had not previously received a diagnosis of atrial fibrillation. 3 About 15% of strokes are attributable to documented atrial fibrillation, and 50 to 60% to documented cerebrovascular disease, 4 – 7 but in about 25% of patients who have ischemic strokes, no etiologic factor is identified. 4 , 8 , 9 Subclinical atrial fibrillation is often suspected to be the cause of stroke in these patients. 10 However, the prevalence and prognostic value of subclinical atrial fibrillation has been difficult to assess. 8 , 9 , 11 , 12 An . . .