The primary objective of this study is to observe the safety and effectiveness of the WATCHMAN FLX™ Left Atrial Appendage Closure (LAAC) Device for subjects with non-valvular atrial fibrillation to reduce the risk of stroke in Hong Kong area.

This study is a prospective, non-randomized, multi-center observational study. The primary Effectiveness Endpoint is the occurrence of non-effective LAA closure defined as any peri-device flow > 5mm demonstrated by TEE/CT/MRI at First Follow-up.The primary safety endpoint is the occurrence of one of the following events between the time of implant and within 7 days following the procedure or by hospital discharge, whichever is later: all-cause death, ischemic stroke, systemic embolism, or device or procedure related events requiring open cardiac surgery or major endovascular intervention such as pseudoaneurysm repair, AV fistula repair, or other major endovascular repair. Secondary effectiveness endpoint is the occurrence of ischemic stroke or systemic embolism at 12 months from the time of implant.

Inclusion Criteria:

1. Patients who are eligible for a WATCHMAN FLX device according to current international and local guidelines (and future revisions) and per physician discretion;
2. Patients who are willing and capable of providing informed consent, participating in all testing associated with this clinical investigation at an approved clinical investigational center;
3. Patients whose age is 18 years or above, or of legal age to give informed consent specific to state and national law.

Exclusion Criteria:

1. Patients who are currently enrolled in another investigational study or registry that would directly interfere with the current study, except when the patient is participating in a mandatory governmental registry, or a purely observational registry with no associated treatments. Each instance should be brought to the attention of the sponsor to determine eligibility.
2. Women of childbearing potential who are, or plan to become, pregnant during the time of the study (method of assessment upon physician's discretion);
3. The subject is unable or not willing to complete follow-up visits and examination for the duration of the study.

Subjects with non-valvular atrial fibrillation to reduce the risk of stroke

0-12months post LAAC.