NCT05963698 · Hamilton Health Sciences Corporation
The Fourth Left Atrial Appendage Occlusion Study
(LAAOS-4)
What this study is about
LAAOS-4 aims to determine if catheter-based endovascular left atrial appendage occlusion prevents ischemic stroke or systemic embolism in participants with atrial fibrillation, who remain at high risk of stroke, despite receiving ongoing treatment with taken by mouth anticoagulation.
View original scientific description
LAAOS-4 aims to determine if catheter-based endovascular left atrial appendage occlusion prevents ischemic stroke or systemic embolism in participants with atrial fibrillation, who remain at high risk of stroke, despite receiving ongoing treatment with oral anticoagulation.
Who can participate
This study lists these criteria on ClinicalTrials.gov. A study coordinator reviews eligibility during screening — this page does not determine whether you qualify.
Inclusion criteria
- (a) Persistent or permanent atrial fibrillation OR (b) Paroxysmal atrial fibrillation in participants with a history of ischemic stroke or systemic embolism
- Increased risk of stroke, defined as a CHA2DS2-VASc stroke risk score of ≥ 4. \[Note: the acronym CHA2DS2-VASc stands for congestive heart failure, hypertension, age ≥75 (doubled), diabetes, stroke (doubled), vascular disease, age 65 to 74 and sex category (female).\]
- 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
- Age \< 18 years
- Current left atrial appendage thrombus
- Prior left atrial appendage occlusion or removal (surgical or percutaneous)
- Prior percutaneous atrial septal defect or patent foramen ovale closure
- Prior atrial fibrillation ablation unless evidence of recurrent qualifying atrial fibrillation present at least 30 days following ablation
- Planned atrial fibrillation 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
- Patient unable or willing to give informed consent
Where
- Birmingham, Alabama
- Jonesboro, Arkansas
- Fountain Valley, California
- Loma Linda, California
- Pasadena, California
- Sacramento, California
- Atlantis, Florida
- Jacksonville, Florida
- Largo, Florida
- Ocala, Florida
- Tampa, Florida
- Atlanta, Georgia
And 36 more locations — see the full list below.
Frequently asked questions
What is a clinical trial?
A clinical trial is a research study that tests new medical treatments, drugs, devices, or procedures to determine their safety and effectiveness. Trials are carefully designed and monitored to protect participants while advancing medical knowledge.
Is it safe to participate?
Clinical trials follow strict safety guidelines and ethical standards. Trials must be reviewed and approved, and participants are closely monitored by medical professionals throughout the study. You can withdraw at any time if you choose.
Will I be compensated?
Many clinical trials offer compensation for your time, travel expenses, and inconvenience. The specific compensation varies by study and will be discussed during the screening process. All study-related medical care is typically provided at no cost to participants.
Will I receive a placebo instead of treatment?
When effective treatment exists, participants typically receive either the standard treatment plus the study intervention, or the standard treatment plus placebo. You would not be denied effective care. Placebos are primarily used when no proven treatment is available, or in addition to standard care. Your trial consent form will clearly explain what treatments you may receive.
Can I leave a trial if I change my mind?
Absolutely. Participation in clinical trials is completely voluntary. You have the right to withdraw from the study at any time, for any reason, without penalty or loss of benefits to which you are otherwise entitled.
How long does a clinical trial last?
Trial duration varies widely depending on the study design and purpose. Some trials last just a few weeks, while others may continue for months or years. The study coordinator will provide specific timeline information during your screening call.
Data: ClinicalTrials.gov · synced Jun 8, 2026 · Source of record for eligibility and locations