The association between CIED-detected atrial tachyarrhythmias of variable durations and stroke or systemic thromboembolism has been evaluated by several studies that overall collected data on > 22,000 patients, taking into account the maximum duration of AHRE episode, or the maximum daily AF burden (ie, the maximum time spent in adjudicated AF in 1 day of the follow-up period).371,379-387 The studies show that AHRE burden with a duration $ 5 to 6 min are signi cantly associated with an increase in the risk of stroke or systemic thromboembolism (HR, 2-9). In a re-analysis of the ASSERT study,388 the increase in the risk of stroke occurred only when the longest duration of the various episodes of detected AHREs was > 24 h. The largest dataset of patients with CIED-detected AHREs was analyzed in the Stroke Prevention Strategies Based on Atrial Fibrillation Information From Implanted Devices [SOS AF] project, with a pooling of 3 prospective studies (Phase IV Long Term Observational Study of Patients Implanted With Medtronic CRDM Implantable Cardiac Devices [PANORAMA], Italian Clinical Services Project, and A Prospective Study of the Clinical Signi cance of Atrial Arrhythmias Detected by Implanted Device Diagnostics [TRENDS]) resulting in During a median follow-up of 24 months, 43% of an unselected cohort of patients with implanted devices experienced $ 1 day with $ 5 min of AHRE burden, and a 1-h threshold of AHRE burden was associated with an HR for ischemic stroke of 2.11 (95% CI, 1.22-3.64; P .008), although the absolute risk of ischemic stroke in patients with AHREs was low (0.39% annual rate in the whole cohort). 