About 20–30% of all strokes are due to AF. A growing number of patients with stroke are diagnosed with “silent” paroxysmal AF. It is recommended to interrogate pacemakers and implantable cardioverter-defibrillators (ICDs) on a regular basis for atrial high rate episodes (AHREs). Patients with AHREs should undergo further electrocardiogram (ECG) monitoring to document AF before initiating AF therapy (Class I, Level of Evidence B). ECG documentation is required to establish the diagnosis of AF (Class I, Level of Evidence B). There is good evidence that prolonged ECG monitoring enhances the detection of undiagnosed AF, e.g., monitoring for 72 hours after a stroke, or even longer periods. By accepted convention, an episode lasting at least 30 seconds is diagnostic. - See more at: http://www.acc.org/latest-in-cardiology/ten-points-to-remember/2016/09/14/14/33/2016-esc-guidelines-for-the-management-of-atrial-fibrillation#sthash.7xmvNmFQ.dpuf