Left Atrial Appendage Occlusion Study III (LAAOS III)

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.

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.

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.

Surgeon will occlude the left atrial appendage using a suture and/or a surgical stapler or a regulatory approved atrial appendage closure during the patient's cardiac surgery procedure.

First occurrence of ischemic stroke or transient ischemic attack with positive neuroimaging or systemic arterial embolism

All cause stroke or transient ischemic attack with positive neuroimaging or systemic arterial embolism

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

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

Ischemic stroke or transient ischemic attack with positive neuroimaging or systemic arterial embolism > 30 days after 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)

Inclusion Criteria: Greater than 18 years of age Undergoing a clinically indicated cardiac surgical procedure with the use of cardiopulmonary bypass Have a documented history of atrial fibrillation or atrial flutter CHA2DS2-VASc score ≥ 2 Have provided informed consent Exclusion Criteria: Patients undergoing off-pump cardiac surgery 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 Patients who have had a previous placement of a percutaneous left atrial appendage closure device

Whitlock RP, Belley-Cote EP, Paparella D, Healey JS, Brady K, Sharma M, Reents W, Budera P, Baddour AJ, Fila P, Devereaux PJ, Bogachev-Prokophiev A, Boening A, Teoh KHT, Tagarakis GI, Slaughter MS, Royse AG, McGuinness S, Alings M, Punjabi PP, Mazer CD, Folkeringa RJ, Colli A, Avezum A, Nakamya J, Balasubramanian K, Vincent J, Voisine P, Lamy A, Yusuf S, Connolly SJ; LAAOS III Investigators. Left Atrial Appendage Occlusion during Cardiac Surgery to Prevent Stroke. N Engl J Med. 2021 Jun 3;384(22):2081-2091. doi: 10.1056/NEJMoa2101897. Epub 2021 May 15.