The primary objective of this study is to determine if left atrial appendage closure with the WATCHMAN FLX Device is a reasonable alternative to oral anticoagulation following percutaneous catheter ablation for high risk patients with non-valvular atrial fibrillation.

This study is a prospective, randomized, multi-center, global investigation to determine if left atrial appendage closure with the WATCHMAN FLX Device is a reasonable alternative to oral anticoagulation in patients after AF ablation.

A subject who signs informed consent is considered enrolled in the study. Subjects will be randomized to OAC or WATCHMAN FLX in equal fashion. Randomization will be stratified by sequential vs. concomitant planned ablation +/- WATCHMAN implantation, to help ensure balance of treatment assignments within the sequential and concomitant groups.

Inclusion Criteria:

1. The subject is of legal age to participate in the study per the laws of their respective geography.
2. Underwent a prior catheter ablation procedure for non-valvular AF between 90 and 180 days prior to randomization (sequential) or is planning to have clinically indicated catheter ablation within 10 days of randomization (concomitant).
3. The subject has a calculated CHA2DS2-VASc score of 2 or greater for males or 3 or greater for females.
4. The subject is deemed to be suitable for the defined protocol pharmacologic regimen.
5. The subject is able to undergo TEE examinations.
6. The subject or legal representative is able to understand and is willing to provide written informed consent to participate in the trial.
7. The subject is able and willing to return for required follow-up visits and examinations.

Exclusion Criteria:

1. The subject is currently enrolled in another investigational study that would directly interfere with the current study, except when the subject is participating in a mandatory governmental registry, or a purely observational registry with no associated treatments. Each instance must be brought to the attention of the sponsor to determine eligibility, regardless of type of co-enrollment being proposed.
2. The subject requires long-term anticoagulation therapy for reasons other than AF-related stroke risk reduction, for example due to an underlying hypercoagulable state (i.e., even if the device is implanted, the subjects would not be eligible to discontinue OAC due to other medical conditions requiring chronic OAC therapy).
3. The subject is deemed by the treating physician to be unsuitable for chronic anticoagulation and/or aspirin therapy due to bleeding risk, allergy, or other reasons.
4. The subject had or is planning to have any cardiac or major non-cardiac interventional or surgical procedure (excluding non-valvular AF ablation and cardioversion) within 30 days prior to or 60 days after randomization [including, but not limited to: percutaneous coronary intervention (PCI), other cardiac ablation (VT ablation, etc.), etc.].
5. The subject had a stroke or transient ischemic attack (TIA) within the 60 days prior to randomization.
6. The subject had a prior major bleeding event per ISTH definition within the 14 days prior to randomization. Lack of resolution of related clinical sequelae, or planned and pending interventions to resolve bleeding/bleeding source, are a further exclusion regardless of timing of the bleeding event.
7. The subject has had a myocardial infarction (MI) documented in the clinical record as either a non-ST elevation MI (NSTEMI) or as an ST-elevation MI (STEMI), with or without intervention, within 90 days prior to randomization.
8. The subject has a history of atrial septal repair or has an ASD/PFO device.
9. The subject has an implanted mechanical valve prosthesis in any position.
10. The subject is of childbearing potential and is, or plans to become pregnant during the time of the study (method of assessment upon study physician's discretion)
11. The subject has a documented life expectancy of less than two years.
12. The subject has a cardiac tumor.
13. The subject has signs/symptoms of acute or chronic pericarditis.
14. There is evidence of tamponade physiology.
15. Contraindications (anatomical or medical) to percutaneous catheterization procedures.
16. The subject has documented NYHA Class IV heart failure.
17. The subject has documented surgical closure of the left atrial appendage.
18. The subject has an active infection.