AMPLATZER PFO Occluder Post Approval Study

Inclusion Criteria: • Subjects with a PFO who have had an ischemic stroke within the last 547 days Exclusion Criteria: * Atherosclerosis or other arteriopathy of the intracranial and extracranial vessels associated with a ≥ 50% lumen diameter supplying the involved lesion * Intra-cardiac thrombus or tumor * Documented evidence of venous thrombus in the vessels through which access to the PFO is gained * Acute or recent (within 6 months prior to consent) myocardial infarction or unstable angina * Left ventricular aneurysm or akinesis * Mitral valve stenosis or severe mitral regurgitation requiring intervention irrespective of etiology * Aortic valve stenosis (mean gradient \>40 mmHg) or severe aortic valve regurgitation * Mitral or aortic valve vegetation or prosthesis * Aortic arch plaques protruding greater than 4mm into the aortic lumen * Left ventricular dilated cardiomyopathy with depressed left ventricular ejection fraction (LVEF less than 35%) * Subjects with other source of right to left shunts, including an atrial septal defect and/or fenestrated septum * Chronic, persistent, or paroxysmal atrial fibrillation or atrial flutter * Pregnancy at the time of implant * Age less than 18 years or greater than 60 years at time of consent * Active endocarditis or other untreated infections * Organ failure (kidney, liver or lung). Kidney failure: Poor urine output of less than 1 cc/kg/hr with elevated BUN levels (above the normal reference range for the laboratory at the investigational site). Liver failure: Liver enzymes outside the normal reference range for the laboratory at the investigational site: poor liver function as assessed by elevated PT (above the normal reference range for the laboratory at the investigational site) and low total protein and albumin (below the normal reference range for the laboratory at the investigational site). Lung failure: Respiratory failure is retention of carbon dioxide more than 60 mmHg, poor oxygenation with oxygen tension less than 40 mmHg in room air or the need for assisted ventilation. * Uncontrolled hypertension defined as sustained elevated systemic blood pressure to more than 160/90 mmHg with medications * Uncontrolled diabetes defined as continued elevated glucose levels in spite of administration of insulin/levels of more than 200 mg with presence of glucose in the urine * Diagnosis of lacunar infarct probably due to intrinsic small vessel as qualifying stroke event Definition: Ischemic stroke in the distribution of a single, small deep penetrating vessel in a patient with any of the following: 1) a history of hypertension (except in the first week post stroke); 2) history of diabetes mellitus; 3) Age \>/= 50; or 4) MRI or CT shows leukoaraiosis greater than symmetric, well-defined periventricular caps or bands (European Task Force on Age-Related White Matter Changes rating scale score \> 0) * Arterial dissection as cause of stroke * Subjects who test positive with one of the following hypercoagulable states; Anticardiolipin Ab of the IgG or IgM (≥30), Lupus anticoagulant, B2-glycoprotein-1 antibodies (≥30) or persistently elevated homocysteine (\>20) * Unable to take antiplatelet therapy * Anatomy in which the AMPLATZERTM PFO Occluder device size required would interfere with intracardiac or intravascular structures such as valves or pulmonary veins * Vasculature, through which access to the PFO is gained, is inadequate to accommodate the appropriate sheath size * Malignancy or other illness where life expectancy is less than 2 years * Subjects who will not be available for follow-up for the duration of the trial * Inability to obtain Informed Consent from patient * Index stroke of poor outcome (modified Rankin score greater than 3)