Evaluation of the STARFlex® Septal Closure System in Patients With a Stroke or TIA Due to the Possible Passage of a Clot of Unknown Origin Through a Patent Foramen Ovale (PFO)

Major Inclusion Criteria: Age 18-60 years inclusive. Positive contrast valsalva bubble study by trans-esophageal echocardiogram (TEE) for patent foramen ovale (PFO), with or without atrial septal aneurysm. Stroke or clinically definite TIA (contact study coordinator). Be able to comply with follow up over two years. Be competent to, or have a legal guardian competent to, provide informed consent following full disclosure of risks and benefits of both treatment arms by a study investigator. Venous access capable of accepting a 10F minimum vascular sheath. Have, or be willing to, discontinue hormonal based contraceptive use prior to enrollment and for the term of the study. Has cardiac anatomy based on enrollment echocardiogram that will allow for placement of the implant if randomized to the implant arm. Note: Additional inclusion criteria may apply. Contact study coordinator or principal investigator for details. Post-randomization - device patients only The size of the PFO (measured by indentation with a soft balloon) must be amenable to selection of a STARFlex device. Major Exclusion Criteria: Carotid artery stenosis > 50%. Intracranial stenosis > 50% appropriate to symptoms. Complex aortic arch atheroma with high risk features for embolism Aortic arch, carotid or vertebral artery dissection. Mitral or aortic valve stenosis, vegetation, or calcification > 5 mm mitral annular calcification (MAC) thickness. Active pregnancy. Active infections (contact study coordinator). Active infective endocarditis or bacteremia. Prosthetic heart valves in any location. Anterior MI within 3 months of neurological event. Chronic atrial fibrillation Thrombus in, or occluded, venous access route. Contraindication to heparin, aspirin, clopidogrel, or warfarin, or a known medical condition that requires continuous warfarin. Patient enrolled in another investigation study where clinical endpoint interference may occur. Permanent pacemaker or inferior vena cava (IVC) filter. Serum creatinine > 2.0 mg/dL Patients with known vasculitis or neurologic disorder. Baseline modified Rankin score of 3 or more. Hypercoagulopathies requiring long-term warfarin. Note: Additional exclusion criteria may apply.