The primary objective of this study is to assess the efficacy and safety of using intra-procedural intracardiac echocardiography (ICE) for WATCHMAN FLX Device implants in subjects with non-valvular atrial fibrillation to reduce the risk of stroke.

Inclusion Criteria:

1. The subject is of legal age to participate in the study per the laws of their respective geography;
2. The subject has documented paroxysmal, persistent, permanent or long-term/longstanding persistent non-valvular atrial fibrillation (i.e., the subject does not have mitral stenosis or a mechanical heart valve);the subject has not been diagnosed with rheumatic mitral valvular heart disease);
3. The subject is deemed by the treating physician to be suitable for the protocol defined pharmacologic regimens;
4. The subject has a calculated CHA2DS2-VASc score of 2 or greater;
5. The subject is able to undergo ICE examinations;The subject is able to undergo ICE(which will be used during the index procedure) and TEE (which will be performed at 45 days and may also be performed at baseline);
6. The subject is able to understand and 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. Subjects who are currently enrolled in another investigational study or registry 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 hypercoaguable 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 warfarin therapy);
3. The subject has a history of atrial septal repair or has an ASD/PFO device;
4. The subject has an implanted mechanical valve prosthesis in any position;
5. The subject currently or has had any documented history of, New York Heart Association Class IV Congestive Heart Failure;
6. 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).