Left Atrial Appendage Occlusion Study III (LAAOS III)

• All cause stroke or transient ischemic attack with positive neuroimaging or systemic arterial embolism [ Time Frame: Common termination point (median follow-up of 4 years) ]
  All cause stroke or transient ischemic attack with positive neuroimaging or systemic arterial embolism
• Ischemic stroke or transient ischemic attack with positive neuroimaging or systemic arterial embolism or death [ Time Frame: Common termination point (median follow-up of 4 years) ]
  Ischemic stroke* or transient ischemic attack with positive neuroimaging or systemic arterial embolism or death
• Ischemic stroke or transient ischemic attack with positive neuroimaging or systemic arterial embolism > 30 days after surgery [ Time Frame: Common termination point (median follow-up of 4 years) ]
  Ischemic stroke or transient ischemic attack with positive neuroimaging or systemic arterial embolism > 30 days after surgery
• Total mortality [ Time Frame: Common termination point (median follow-up of 4 years) ]
  Total mortality

• Total mortality [ Time Frame: Common termination point (median follow-up of 4 years) ]
  Total mortality
• Operative safety outcomes [ Time Frame: 30 days post-surgery ]
  Operative safety outcomes (30-day mortality, chest tube output in the first post-operative 24 hours, rate of post-operative re-exploration for bleeding)
• Readmission for heart failure [ Time Frame: Common termination point (median follow-up of 4 years) ]
  Readmission for heart failure
• Major bleed [ Time Frame: Common termination point (median follow-up of 4 years) ]
  Major bleed

• Readmission for heart failure [ Time Frame: Common termination point (median follow-up of 4 years) ]
  Readmission for heart failure
• Post-operative safety outcomes [ Time Frame: 30 days post-surgery ]
  Operative safety outcomes (30-day mortality, chest tube output in the first post-operative 24 hours, rate of post-operative re-exploration for bleeding)
• Major bleeding [ Time Frame: Common termination point (median follow-up of 4 years) ]
  Major bleeding
• Myocardial infarction [ Time Frame: Common termination point (median follow-up of 4 years) ]
  Myocardial infarction

Atrial fibrillation (AF) is a common heart rhythm disorder that leads to one-sixth of all strokes. Prevention of strokes in AF is achieved through the use of blood thinners such as coumadin. Although these blood thinners are effective, they are limited by the risk of serious bleeding, by physician and patient reluctance to use, and by noncompliance and discontinuation. The left atrial appendage is a structure on the upper chamber of the heart that is the most common source of stroke in patients with AF. This structure is easily accessible during open heart surgery for removal, and has been an area of interest for stroke prevention. However, there is currently no strong evidence that removing it works.

The LAAOS III trial will randomly (like the flip of a coin) assign patients with AF undergoing heart surgery for other reasons to have the left atrial appendage removed or not. These patients, other than this small procedure which has been shown to be quite safe, will be treated in the usual manner. The full study of 4700 patients, followed for an average of 4 years, will determine if removing the left atrial appendage can reduce stroke and other complications on top of usual therapy. A positive study will change the way heart surgery is performed on AF patients and results in a large reduction in the number of strokes in a large population. Further, it will promote further research into this approach that could be applied beyond AF patients undergoing heart surgery.

• Cardiac Surgery With Cardiopulmonary Bypass
• Atrial Fibrillation

• Experimental: Left Atrial Appendage Occlusion Group
  Surgeon will close the left atrial appendage using a suture and/or a surgical stapler or a regulatory approved atrial appendage closure device during the patient's cardiac surgery procedure.
  Intervention: Other: Left Atrial Appendage Occlusion
• No Intervention: No Left Atrial Appendage Occlusion Group
  Surgeon will not close the left atrial appendage during the patient's cardiac surgery procedure. Patient will be treated as per best medical practice for stroke prevention in atrial fibrillation. Treatment will be decided by the patient's primary care physician.

Inclusion Criteria:

1. Greater than 18 years of age
2. Undergoing a clinically indicated cardiac surgical procedure with the use of cardiopulmonary bypass
3. Have a documented history of atrial fibrillation or atrial flutter
4. CHA2DS2-VASc score ≥ 2
5. Have provided informed consent

Exclusion Criteria:

1. Patients undergoing off-pump cardiac surgery

2. Patients undergoing any of the following procedures:

   • heart transplant
   • complex congenital heart surgery
   • sole indication for surgery is ventricular assist device insertion
   • previous cardiac surgery requiring opening of the pericardium
   • mechanical valve implant
3. Patients who have had a previous placement of a percutaneous left atrial appendage closure device