This study will assess the safety and effectiveness of GORE® CARDIOFORM Septal Occluder in a post approval setting and evaluate the quality of operator education and training and transferability of trial experience to a post-market setting.

A maximum of 636 adult subjects will be enrolled at up to 40 U.S. centers. Subjects will have follow-up at 1 month, 6 months, 12 months and annually thereafter through 5 years post implant.

Inclusion Criteria:

• Diagnosed with an ischemic stroke presumed to be an embolic stroke of undetermined source (ESUS) verified by a neurologist within the last 365 days prior to enrollment.
• Presence of Patent Foramen Ovale (PFO), as determined initially by positive bubble study utilizing transesophageal echocardiography (TEE) and/or transcranial Doppler (TCD), demonstrating spontaneous right-to-left shunting or right-to-left shunting during Valsalva maneuver.
• Patient is able to tolerate antiplatelet therapy
• Note: Additional Inclusion Criteria may apply

Exclusion Criteria:

• History of or ongoing atrial fibrillation/flutter
• Other co-morbidities including, but not limited to, mural thrombus, dilated cardiomyopathy, cardiac prosthetics (valves), severe native valve disease (including mitral valve stenosis), severe ventricular wall motion abnormalities, aortic dissection, significant atherosclerosis, vasculitis, pre-existing non-vascular neurologic disorders, pulmonary arteriovenous malformations, prior intracranial hemorrhage, severe disability related to prior stroke, autoimmune disorders that would increase the risk of stroke or thromboembolism, or associated with increased risk of infection or procedural complications, in the opinion of the investigator, left ventricular ejection fraction of <40%, coexistent cause or intra-cardiac shunting (e.g. VSD or ASD)
• Previous Myocardial Infarction
• Rankin Scale sore greater than or equal to 3 at the time of procedure
• Active infection that cannot be treated successfully prior to enrollment
• Neurological deficits not due to stroke that may affect the patient's neurologic assessments
• Evidence of hypercoagulable state, Uncontrolled diabetes mellitus, uncontrolled systemic hypertension or pulmonary hypertension at the time of screening or procedure
• Sensitivity or contraindication to all proposed medical treatments or any device components
• Pregnant, lactating, or intent on becoming pregnant through 24 months after enrollment.
• Indications outside the parameters accepted for placement of GSO, including extensive congenital cardiac anomalies and defect diameters considered too large for closure with the device.
• Atrial septal anatomy that is expected to necessitate placement of more than one GORE® CARDIOFORM Septal Occluder
• Need for concomitant procedure(s) that may confound detection of adverse events related to device placement
• Note: Additional Exclusion Criteria may apply