Using Left Atrium Appendage Closure in NVAF Patients With High Risk of Ischemic Stroke

Inclusion Criteria: * Non valvular atrial fibrillation subjects aged ≥18 and ≤80; * High risk of ischemic stroke: CHA2DS2VASc score ≥ 2 ( ≥ 3 for female) together with any of the following circumstances: 1. With a recorded history (happened earlier than 6 months from now) of bleeding (including gingival/nasal/oral bleeding, skin \&soft tissue bleeding, gastrointestinal bleeding, urinary tract bleeding, cerebral haemorrhage, etc.) or bleeding tendency; 2. Intolerance or rejection of long-term anti-coagulation therapy; 3. Suffering stroke or embolism despite routine anti-coagulation therapy; 4. With a predicting HAS-BLED score ≥3. * Subjects (or his/her legal representatives) are able to understand the study objectives, willing to cooperate with procedure and follow-up. Subjects who voluntarily participate in this trial and have signed the written informed consent form. Exclusion Criteria: * Subjects with atrial fibrillation (AF) caused by rheumatic valvular disease, moderate to severe mitral stenosis, severe mitral regurgitation, severe aortic valve disease or severe left ventricular outflow tract obstruction with pressure difference greater than 40mmHg; * Suffering with other disease(s) requiring long-term oral anticoagulation treatment; * Initial untreated AF, or secondary AF with clear cause (such as hyperthyroid heart disease); * Intracardiac thrombus (including left and/or right atrium) found or persisted; * Suffered with myocardial infarction within 3 months; * History of previous atrial septum repair operation or Atrial Septal Occluder implantation; * History of previous heart valve (mechanical valve) replacement operation; * Subjects undergoing heart transplant operation; * Subjects with symptomatic carotid artery disease (such as carotid stenosis \> 50%) or subjects with vulnerable carotid artery plaque. * Suffered with ischemic stroke or TIA recently (within 30 days); * Known complex active atherosclerotic plaque(s) in the descending aorta or aortic arch; * Severe heart failure (NYHA Grade Ⅳ); * The investigator assessed that there were abnormal result(s) with clinical significance in the routine blood test of subjects； * Severe renal abnormal: serum creatinine \>250μmol/l; or on dialysis; * Allergic or contraindicated to aspirin, clopidogrel, heparin, contrast agent, and nitinol alloy; * Subjects who are scheduled to receive operation within 1 year after procedure, and need to stop anti-thrombotic therapy; * Pregnant or breast-feeding subjects, or subjects who plan to have a child within 1 year after procedure; * Subjects with a life expectancy less than 12 months; * Subjects who are participating in another investigational drug or device clinical trial in which the primary endpoint is still not reached before enrolment; * Subjects have other reasons that cannot maintain 2 months anticoagulation or 6 months dual antiplatelet therapy; * Subjects with poor compliance (judged by investigator) or cannot complete the study according to the protocol due to other reasons; * Subjects who are unsuitable to receive LAA occlusion treatment (judged by investigator).