Subclinical Atrial Fibrillation Is Associated with Increased Stroke Risk

Subclinical atrial fibrillation (AF) is thought to cause some strokes of unknown etiology. To investigate this issue, researchers enrolled 2580 hypertensive patients (age, ≥65) who had recently received pacemakers or implantable cardioverter-defibrillators but had no histories of AF; the devices were programmed to document subclinical atrial tachyarrhythmias (defined as an atrial rate >190 beats/minute and a duration of ≥6 minutes). At 3 months, the devices were interrogated to determine the incidence of these subclinical atrial arrhythmias, which were assumed to represent silent AF.

Within the 3-month monitoring period, 261 patients (10%) had subclinical atrial tachyarrhythmias. During subsequent follow-up of 2.5 years, incidence of stroke …