LAmbre Versus AMPLATZER Amulet Left AtrIal Appendage Occluder for StRoke ProphylaxIs

Inclusion Criteria: * Age ≥ 18 years and able to give consent * Documented paroxysmal, persistent or permanent non-valvular atrial fibrillation/ atrial flutter (AF) at high risk of stroke or systemic embolism defined by CHA2DS2-VASc score ≥ 2 (male) or ≥ 3 (female) * Patient not eligible for long-term oral anticoagulation therapy * Deemed suitable for percutaneous LAAO * Able to comply with the required medication regimen after LAAO device implantation * Written informed consent * LAA anatomy can accommodate either a LAmbre or AMPLATZER Amulet LAAO device, as per manufacturer's instruction for use (IFU) (the anatomy and sizing must be appropriate for both devices in order to be enrolled in the trial) * For women of childbearing potential, negative pregnancy test and agree to use reliable method of birth control during the study Exclusion Criteria: 1. Indication for long-term oral anticoagulation therapy for a condition other than AF (i. e. pulmonary embolism, mechanical heart valve) 2. LAA is obliterated or surgically ligated 3. Known allergy or hypersensitivity to any component of the LAAO devices or components of the required medication regimen 4. Prior atrial septal defect (ASD) repair or implantation of ASD closure device 5. Active endocarditis or other infection producing bacteremia 6. Significant symptomatic carotid artery disease 7. Participation in a concurrent clinical trial, which may confound the results of this trial 8. Patient cannot adhere to or complete the trial protocol for any reason Or any of the following echocardiographic exclusion criteria: 9. Intracardiac thrombus 10. Intracardiac tumor 11. Existing, clinically relevant circumferential pericardial effusion 12. Significant mitral valve stenosis