**The Fourth Left Atrial Appendage Occlusion Study (LAAOS-4)** is a research project checking if a special procedure can help prevent strokes in people with a heart problem called atrial fibrillation. This condition makes the heart beat irregularly, which might increase the risk of a stroke. Even if patients are already taking medicine called anticoagulants to lower stroke risk, they might still be in danger. The study uses a method called "catheter-based endovascular left atrial appendage occlusion," which means placing a small device in the heart to block a part called the left atrial appendage. This part can form clots that might cause a stroke. **Key Points to Consider:** - **Study Duration:** The trial requires participants to be on anticoagulants for at least 90 days before joining and to continue during the study. - **Eligibility:** Participants must have a high stroke risk score (CHA2DS2-VASc score of 4 or more) and must be above 18 years old. - **Commitment:** Participants can't plan to stop taking anticoagulants and must agree to all study conditions, including giving informed consent. The study will help see if this new procedure can better protect people at high risk of strokes.