LAAOS-4

The Fourth Left Atrial Appendage Occlusion Study

To determine if catheter-based endovascular left atrial appendage occlusion (LAAO) prevents ischemic stroke or systemic embolism in patients with atrial fibrillation (AF), who remain at high risk of stroke, despite receiving ongoing treatment with oral anticoagulation.

Enrolment Criteria

Inclusion
- One of the following three:
  - Persistent AF;
  - Permanent AF;
  - OR paroxysmal AF with a history of ischemic stroke or systemic embolism
- CHA2DS2-VASc score of ≥ 4
- Treatment with OAC (VKA or factor Xa inhibitor) for at least 90 days prior to enrollment, AND no documented plan to discontinue treatment with OAC for the expected duration of the trial
Exclusion
- Age < 18 years
- Current left atrial appendage (LAA) thrombus
- Prior LAA occlusion or removal (surgical or percutaneous)
- Prior percutaneous atrial septal defect or patent foramen ovale closure^†
- Prior AF ablation unless evidence of recurrent qualifying AF present at least 30 days following ablation
- Planned AF ablation within 90 days of enrollment
- Individuals being treated with direct thrombin inhibitors
- Women of childbearing potential unless they agree to employ effective birth control methods throughout the study
- Anticipated life expectancy of < 2 years
- Unable or unwilling to give informed consent
  ^† Participants with a mechanical heart valve, mitral stenosis, atrial septal defect or a patent foramen ovale are not excluded.