Left Atrial Appendage Occlusion Study II (LAAOSII)

McMaster University, Sunnybrook Health Sciences Centre, London Health Sciences Centre, Université de Montréal

A pilot, multicentre randomized controlled study of surgical left atrial occlusion (LAA) in 50 patients with atrial fibrillation/flutter undergoing cardiac surgery requiring cardiopulmonary bypass with additional risk factors for late stroke. Patients will be enrolled and randomized to undergo LAA exclusion and aspirin therapy or best medical therapy as per guidelines. Main research questions: Can successful occlusion of the LAA be safely achieved by cut and sew or stapler techniques? In patients with atrial fibrillation with 2 or more risk factors for stroke, will removal of the left atrial appendage (LAA) and aspirin therapy reduce the risk of systemic embolic events and major bleeding compared to warfarin?

The number one cause of disability and the 3rd leading cause of death in patients with atrial fibrillation (AF) is stroke. Echocardiographic studies suggest that the predominant source of stroke in AF is the left atrial appendage (LAA). At present, there are no sufficiently powered trials to answer whether removal of the LAA can reduce the risk of systemic embolic events. LAAOS pilot study will recruit 50 participants undergoing open-heart surgery in 5 Canadian academic cardiac surgery centers. The study will inform the feasibility of conducting a large RCT and will provide information of the efficacy and safety of appendage occlusion technique. From this study we envision a a large international randomized controlled trial (LAAOS II) to determine the impact of left atrial appendage occlusion on the composite outcome of stroke and non-central nervous system systemic embolic events in at risk patients with atrial fibrillation undergoing cardiac surgery.

Surgical intervention: Occlusion of the left atrial appendage (LAA) using 'cut-and-sew' technique appendage occlusion.

Medical arm: The comparator is best medical practice for atrial fibrillation related stroke prevention as per guidelines.

Study intervention: Within the trial, occlusion must be performed using either amputation and closure (cut and sew) or stapler device.

Demonstration of efficacy of cut-and-sew and stapler technique of appendage occlusion by intraoperative transesophageal echocardiography, central adjudication.

Demonstration of study feasibility, procedure safety, including rate of post-operative re-exploration for bleeding.

Inclusion Criteria: Adult patients undergoing any cardiac surgical procedure with the use of cardiopulmonary bypass A history of ECG-documented atrial fibrillation with prior stroke or TIA, or at least two of the following risk factors: age => 65 years hypertension diabetes mellitus, or heart failure/left ventricular ejection fraction < 50% Exclusion Criteria: Patients in whom surgical AF ablation (MAZE or otherwise) is planned Planned "off-pump" surgery Planned implantation of a mechanical valve Heart transplant, complex congenital heart surgery, and ventricular assist device insertion, reoperation