Occult Paroxysmal Atrial Fibrillation in Non-Cryptogenic Ischemic Stroke

Inclusion Criteria: * Patients with a recent ischemic stroke or transient ischemic attack (TIA) with brain infarction on brain imaging. * No history of atrial fibrillation or finding of atrial fibrillation on standard inpatient monitoring (electrocardiogram, telemetry, 24-hour Holter monitor) * Have a presumed stroke etiology: Lacunar or small vessel thrombosis, extra-cranial or intracranial atherosclerotic stenosis or dissection, arteriopathy or vasculitis, hypercoagulable state, aortic arch plaque with or without mobile elements, or evidence of a low-risk cardiac source (e.g., patent foramen ovale with or without atrial septal aneurysm and with or without evidence of venous thromboembolic source). * Have virtual CHADS2 score ≥3 or * Have 2 or more of the following co-morbidities: obstructive sleep apnea, coronary artery disease, (Chronic Pulmonary Obstructive Disease (COPD), hyperthyroidism, Body Mass Index\> 30, prior myocardial infarction, prolonged PR interval (\>175 ms) or renal impairment (GFR 30-60). * Patient or legally authorized representative who is willing to sign written consent form. * Patient is ≥40 years old (patients younger than 40 years old have a very low likelihood of having atrial fibrillation and are therefore excluded from the study). * Patient can have the device implanted within 7 days of the incident ischemic event Exclusion Criteria: * Documented history of AF or atrial flutter. * Evidence of a high-risk cardiac source of embolism (Left Ventricular or Left Atrial thrombus or "smoke," emboligenic valvular lesion or tumor) * Untreated hyperthyroidism. * Myocardial infarction or coronary bypass grafting within 1 month prior to the stroke/TIA. * Valvular disease requiring immediate surgical intervention. * Permanent indication for anticoagulation at enrollment. * Permanent oral anticoagulation contraindication. * Already included in another clinical trial that will affect the objectives of this study. * Life expectancy is less than 1 year. * Pregnancy. Urine or serum pregnancy test is required for women of child bearing potential to exclude pregnancy. * Patient is indicated for implant with a pacemaker, implantable cardioverter-defibrillator, CRT device, or an implantable hemodynamic monitoring system * Patient is not fit, or is unable or unwilling to follow the required procedures of the Clinical Investigation Plan. * Cryptogenic Stroke: A stroke/TIA will be considered cryptogenic if no cause is determined despite extensive inpatient workup according to the standard diagnostic protocol at North Shore University Hospital.