Inclusion Criteria

1. (a) Persistent or permanent AF
   OR
   (b) Paroxysmal AF in participants with a history of ischemic stroke or systemic embolism
2. Increased risk of stroke, defined as a CHA2DS2-VASc score of ≥ 4
3. Treatment with OAC for at least 90 days prior to enrollment, AND no documented plan to permanently discontinue treatment with OAC for the expected duration of the trial
   

Exclusion Criteria

1. Age < 18 years
2. Current left atrial appendage (LAA) thrombus
3. Prior LAA occlusion or removal (surgical or percutaneous)
4. Prior percutaneous atrial septal defect or patent foramen ovale closure*
5. Prior AF ablation unless evidence of recurrent qualifying AF present at least 30 days following ablation
6. Planned AF ablation within 90 days of enrollment
7. Individuals being treated with direct thrombin inhibitors
8. Participants of childbearing potential unless they agree to employ effective birth control methods throughout the study
9. Anticipated life-expectancy of < 2 years
10. Individual unable or unwilling to give informed consent
    *Participants with a mechanical heart valve, mitral stenosis, atrial septal defect, or a patent foramen ovale are not excluded.