Inclusion Criteria:  Age ≥18 years.  Diagnosis of acute ischemic stroke or transient ischemic attack (TIA) (WHO definition) of undetermined etiology made by neurologist within 7 days after the index event. The event must be either:  an ischemic stroke confirmed by neuroimaging; or a TIA, defined as involving a focal unilateral motor deficit, speech/language deficit or hemianopia, with symptom duration <24 hours (note: amaurosis fugax/ transient monocular blindness, pure sensory spells, isolated vertigo spells, etc. do not qualify for enrolment given the potential for misdiagnosis of such events). No AF detected in baseline 12-lead ECG on admission.  The following diagnostic test have already been completed as part of clinical routine post-stroke/TIA:  Brain imaging with CT or MRI, Transthoracic echocardiography to congenital heart disease and endocarditis. Recurrent stroke/TIA is inclusionary as long as patient meets inclusion/exclusion criteria for study enrolment.  Exclusion Criteria:  Stroke of unknown time of symptom onset. Modified Rankin Scale ≥5 on index admission. Previous documented history of primary intracerebral bleeding. Previous documented history of AF or atrial flutter (a remote history of transient AF during perioperative period is not exclusionary). Skin allergies, conditions, or sensitivities to cardiac patch. Exclusively retinal stroke or retinal TIA event. Pre-existing indication for anticoagulation (eg. History of mechanical heart valve replacement, deep vein thrombosis). Pre-existing contraindication for permanent anticoagulation (eg. hypocoagulable state). Echocardiographic findings of congenital heart disease and endocarditis. Indicated for pacemaker, implantable cardiac defibrillator (ICD), CRT device, or an implantable hemodynamic monitoring system. Intravenous drug users (IVDUs). Life expectancy < 1 year for reasons other than stroke (eg. Metastatic cancer disease). Concomitant participation in other clinical trials involving investigational medications. Pregnancy.