Home › Trials › NCT05963698

Catheter-based closure of the left atrial appendage to prevent strokes in patients with atrial fibrillation

The Fourth Left Atrial Appendage Occlusion Study (LAAOS-4)

NA · Hamilton Health Sciences Corporation · NCT05963698

This study is testing if a new catheter procedure using the WATCHMAN device can help prevent strokes in patients with atrial fibrillation who are still at high risk despite taking blood thinners.

Quick facts

PhaseNA
Study typeInterventional
Enrollment4000 (estimated)
Ages18 Years and up
SexAll
SponsorHamilton Health Sciences Corporation (other)
Locations127 sites (Birmingham, Alabama and 126 other locations)
Trial IDNCT05963698 on ClinicalTrials.gov

What this trial studies

The Fourth Left Atrial Appendage Occlusion Study (LAAOS-4) is a multicenter, prospective, open-label, randomized controlled trial designed to evaluate the effectiveness of catheter-based endovascular left atrial appendage occlusion in preventing ischemic stroke or systemic embolism in patients with atrial fibrillation. Participants will be those at high risk for stroke despite ongoing treatment with oral anticoagulants. The study will utilize the WATCHMAN device for the occlusion procedure, with endpoints assessed in a blinded manner to ensure objectivity. This approach aims to provide a new intervention for patients who remain at risk despite standard anticoagulation therapy.

Who should consider this trial

Good fit: Ideal candidates include adults with persistent or permanent atrial fibrillation or paroxysmal atrial fibrillation and a history of ischemic stroke or systemic embolism, who have a CHA2DS2-VASc score of 4 or higher.

Not a fit: Patients under 18 years old, those with current left atrial appendage thrombus, or individuals who have previously undergone left atrial appendage occlusion or removal will not benefit from this study.

Why it matters

Potential benefit: If successful, this intervention could significantly reduce the incidence of strokes in patients with atrial fibrillation who are at high risk.

How similar studies have performed: Other studies have shown promise with similar catheter-based approaches for left atrial appendage occlusion, indicating a potential for success in this trial.

Eligibility criteria

Show full inclusion / exclusion criteria 
Inclusion Criteria:

1. (a) Persistent or permanent atrial fibrillation OR (b) Paroxysmal atrial fibrillation in participants with a history of ischemic stroke or systemic embolism
2. Increased risk of stroke, defined as a CHA2DS2-VASc stroke risk score of ≥ 4. \[Note: the acronym CHA2DS2-VASc stands for congestive heart failure, hypertension, age ≥75 (doubled), diabetes, stroke (doubled), vascular disease, age 65 to 74 and sex category (female).\]
3. Treatment with oral anticoagulants (Vitamin K agonist or factor Xa inhibitor) for at least 90 days prior to enrollment, AND no documented plan to discontinue treatment with oral anticoagulants for the expected duration of the trial.

Exclusion Criteria:

1. Age \< 18 years
2. Current left atrial appendage thrombus
3. Prior left atrial appendage occlusion or removal (surgical or percutaneous)
4. Prior percutaneous atrial septal defect or patent foramen ovale closure
5. Prior atrial fibrillation ablation unless evidence of recurrent qualifying atrial fibrillation present at least 30 days following ablation
6. Planned atrial fibrillation ablation within 90 days of enrollment
7. Individuals being treated with direct thrombin inhibitors
8. Women of childbearing potential unless they agree to employ effective birth control methods throughout the study
9. Anticipated life-expectancy of \< 2 years
10. Patient unable or willing to give informed consent

Where this trial is running

Birmingham, Alabama and 126 other locations

+77 more sites — see ClinicalTrials.gov for the full list.

Study contacts

How to participate

  1. Review the eligibility criteria above with your treating physician.
  2. Visit the official trial page on ClinicalTrials.gov for the most current contact information and recruitment status.
  3. Contact the listed study coordinator or principal investigator to request pre-screening. Pre-screening is free and never obligates you to enroll.

View on ClinicalTrials.gov →

Conditions: Atrial Fibrillation, Stroke, Ischemic, Systemic Embolism, WATCHMAN, Left Atrial Appendage, LAA Device, Left Atrial Appendage Occlusion

Last reviewed 2026-05-15 by the Find a Trial editorial team. Information on this page is for educational purposes and is not medical advice. Always consult qualified healthcare professionals about clinical trial participation.