Aims: The aim of the study was to evaluate the safety and efficacy of left atrial appendage occlusion (LAAO) with the AMPLATZER Cardiac Plug (ACP) or Amulet using aspirin alone (ASA) as post-implantation antithrombotic treatment. Methods and results: This was a single-centre, prospective, non-randomised study on LAAO with the ACP or Amulet in a consecutive cohort (n=110) treated by ASA alone post implantation. The primary outcome was device-related thrombosis, while secondary outcomes were ischaemic stroke or major bleeding. Clinical follow-up was conducted after six weeks and 12 months with TEE and cardiac CT. One hundred and seven patients were included in the analysis. Three patients were excluded due to a mechanical valve prosthesis. CHA(2)DS(2)-VASc score was 4.4 +/- 1.6 and HAS-BLED 4.1 +/- 1.1. Successful implantation was obtained in all patients with a periprocedural complication rate of 4.6%. Median follow-up was 2.3 years, with a total of 265 patient-years. Device-related thrombosis was detected in 2/107 (1.9%) cases. Stroke occurred in 6/107 patients, with an annualised rate of 2.3%, which is a 61% risk reduction compared to the predicted rate. Annual risk of major bleeding was reduced by 57%. Conclusions: LAAO with the ACP or Amulet was safely performed with ASA monotherapy after implantation without an increased risk of device-related thrombosis or stroke.