Atrial Fibrillation Before and After Patent Foramen Ovale Closure Study

Inclusion Criteria:

1. History of embolic events such as cryptogenic stroke or systemic embolism (singleevent or multiple events). A stroke is considered to be cryptogenic if no possiblecause can be determined despite extensive workup according to the standard protocolof the participating center (TOAST classification 5b) (29). Before inclusion in thestudy, the following tests are required as standard tests to establish the diagnosisof cryptogenic stroke:

• MRI or computed tomography (CT) of the neurocranium (documenting ischemicembolic stroke)

• 12-lead ECG (exclusion of AF)

• Continuous ECG monitoring for at least 7 days (inpatient telemetry orHolter-ECG as an in- or outpatient

• Ultrasonography, CT or MRI angiography of head and neck to rule out arterialdisease as a cause of stroke (see below), or other potential causes of stroke

2. Cardiac monitoring is planned to be performed with the BIOMONITOR III(m) device

3. Presence of right-to-left shunt through a PFO as assessed by means oftransesophageal echocardiography (TEE) with agitated saline while the patient is atrest or while a Valsalva maneuver is being performed.

4. Occlusion of PFO is planned to be performed with the AMPLATZERTM PFO OCCLUDERdevice.

5. Patient is willing to sign patient consent form.

6. Age ≥18 years.

Exclusion Criteria:

1. Known etiology of the embolic event (based on neuro-/cardiac/vascular imaging), suchas:

• Evidence of large-artery atherosclerosis (ultrasonography, CT or MRIangiography, or digital subtraction angiography) with stenosis of 50% or morein the artery feeding the acute ischemic territory.

• Small vessel disease, defined by radiographic appearance consistent withischemic infarction in the territory of a perforating arteriole, with ≤20 mm indiameter on axial sections and not involving the cortex, located in the whitematter, internal or external capsule, deep brain nuclei, thalamus, orbrainstem.

• Evidence of a high-risk cardiac or aortic arch source of embolism (leftventricular or left atrial thrombus or "smoke," emboligenic valvular lesion ortumor, aortic arch plaque >3 mm thick or with mobile components or any otherhigh-risk lesion)

• Stroke of other determined cause such as presence of non-atheroscleroticvasculopathies (i.e. dissection, fibromuscular dysplasia), hypercoagulablestates (must be tested in patients <55 years old) and hematologic disorders

2. Atrial septal defect or ventricular septal defect.

3. Coronary or valvular disease requiring surgical intervention.

4. Documented history of AF or atrial flutter.

5. Permanent indication for therapeutic oral anticoagulation at enrollment.

6. Already included in another clinical trial that will affect the objectives of thisstudy.

7. Life expectancy <1 year.

8. Pregnancy.

9. Patient underwent or is scheduled for implantation of a pacemaker, implantablecardioverter defibrillator or cardiac resynchronization therapy device.

10. Unable or unwilling to follow the required procedures of the Clinical InvestigationPlan.