Ongoing randomized trials comparing NOACs with aspirin in ESUS patients are in progress. Prior to data from these trials, physicians might, in the meantime, consider the use of anticoagulation in parallel with continued cardiac evaluation (eg, prolonged rhythm monitoring) after discussion and consideration of patient preference. AHREs Detected by Cardiac Implanted Electronic Devices Cardiac implanted electrical devices (CIEDs) with an atrial lead or with capability of rhythm discrimination (ie, implantable cardiac monitors) allow continuous monitoring of the cardiac rhythm and appropriate detection of atrial tachyarrhythmias, including AF, as AHREs as well as storing arrhythmia electrograms in the device s memory for review and speci c diagnosis. AHREs, currently de ned as episodes of at least 5 min of atrial tachyarrhythmias/AF with an atrial rate >180 beats/min, are usually asymptomatic, discovered during routine device follow-up, and classi ed in terms of duration of the single episode or time spent in atrial tachyarrhythmias during a day (from minutes to Although temporal cutoffs for detection and storage of AHRE data as short as 30 to 60 s have been used, the diagnostic accuracy is reliable when episodes $ 5 min in duration are considered, since, using this cutoff, the appropriateness in AF detection is 95%, minimizing the risk of over-sensing due to detection of artifacts caused by myopotentials or other sources of electrical Individual patient analysis of electrograms corresponding to AHREs is clinically indicated to exclude artifacts or other causes of inappropriate detection of atrial tachyarrhythmias or AF. 