Left Atrial Appendage Closure as Secondary Prevention of Atrial Fibrillation-related Embolic Events

This study examines whether sealing off a small pouch in the heart called the left atrial appendage (LAA) — using a minimally invasive device — can prevent future strokes in patients with atrial fibrillation (an irregular heartbeat) who have already had a stroke or blood clot and cannot safely take blood thinners long-term. **You may be eligible if...** - You are 18 or older with atrial fibrillation (not caused by a heart valve problem) - You have already had a stroke or blood clot related to atrial fibrillation - You have a high bleeding risk, cannot take blood thinners long-term, have poor compliance with those medications, or have a high stroke risk score **You may NOT be eligible if...** - You have a type of atrial fibrillation caused by heart valve disease - There is a clot already present in your heart - You have had a heart attack in the past 3 months - You have severe heart failure (Class IV) - You are allergic to nitinol, aspirin, clopidogrel, heparin, or other blood thinners - You are pregnant or planning to become pregnant - You have had a stroke or major bleeding in the past 30 days Talk to your doctor to see if this trial is right for you.