The objective of this trial is to compare two different commercially available left atrial appendage occlusion (LAAO) devices in patients with non-valvular Atrial fibrillation/ atrial flutter (AF) at increased risk for stroke with regard to safety and efficacy.

The investigators hypothesize that LAAO using the LAmbre occlusion device (Lifetech Scientific, Shenzhen, China) is non-inferior to LAAO using the AMPLATZER Amulet occlusion device (Abbott Medical, Chicago, ILL, USA) with regards to the primary endpoint, which is peri-device leak (PDL) size 3 months after LAAO, as assessed with transesophageal echocardiography (TOE) in patients with non-valvular AF.

AMPIRI is an investigator-initiated, prospective, randomized, multi-center, open-label, non-inferiority other clinical investigation. All consecutive patients with non-valvular AF at increased risk for stroke or systemic embolism based on CHA2DS2-VASc score not eligible for long-term oral anticoagulation therapy will qualify for screening. Patients with confirmed eligibility and who have given written informed consent will be randomized in a 1:1 fashion to group A (LAmbre LAAO device) or group B (AMPLATZER Amulet LAAO device). Clinical indication, technique, and timing of LAAO will be at the operator's discretion.

The investigators hypothesize that LAAO using the LAmbre occlusion device (Lifetech Scientific, Shenzhen, China) is non-inferior to LAAO using the AMPLATZER Amulet occlusion device (Abbott Medical, Chicago, ILL, USA) with regards to the primary endpoint, which is PDL size 3 months after LAAO, as assessed with TOE in patients with non-valvular AF.

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