Evaluation of the Safety and Efficacy of a Novel SeaLA™ Left Atrial Appendage Occluder

Inclusion Criteria: 1. Patients with nonvalvular paroxysmal, persistent or permanent atrial fibrillation; 2. Subject is not suitable for long-term treatment with anticoagulant; 3. CHA2DS2-VASC score（Atrial fibrillation stroke risk score） ≥ 2; 4. Subjects are suitable for dual antiplatelet therapy for 3 months and complete follow-up; Exclusion Criteria: 1. Patients with atrial fibrillation caused by rheumatic heart valve disease, degenerative heart valve disease, or congenital heart valve disease; 2. Patients after heart transplantation; 3. Unstable angina or recent myocardial infarction \< 3 months; 4. Cardiac function IV (NYHA grade); 5. Subject requires atrial fibrillation catheter ablation surgery within 30 days of LAA occlusion device implantation; 6. Excludes the case of atrial fibrillation catheter ablation and LAA closure in the same surgery (if atrial fibrillation catheter ablation and LAA closure are operated on the same operation, it is recommended to have catheter ablation before closure); 7. Subject has an electrical cardioversion plan within 30 days of LAA occlusion device implantation; 8. After mechanical prosthetic valve implantation; 9. History of stroke or TIA(transient ischemic attack) within 30 days; 10. Thrombocytopenia (platelets≤ 100.000 pcs/mcL); 11. Active endocarditis, sepsis; 12. Heart tumor or other malignant tumor, life expectancy \< 1 year; 13. subjects who are pregnant, lactating or planning to become pregnant during clinical trials (must undergo a pregnancy test before surgery, except for women of non-childbearing age); 14. are currently participating in clinical trials of other drugs or medical devices and have not completed the primary endpoint of the study, which may cause confusion in the results of this study or may affect subjects' compliance with this study follow-up; 15. The subject is subordinate to the sponsor or clinical trial institution or investigator; 16. The investigator judged that the subject's compliance was poor and could not complete the clinical trial requirements; 17. Allergy to nitinol or contrast media; 18. There is a complex movable/ruptured/\> 4mm atherosclerotic plaque at the ascending aorta/aortic arch; 19. Patients with symptomatic carotid artery stenosis (such as carotid artery stenosis greater than 50%);