Occlusion of the left atrial appendage (LAA) is a potential alternative to anticoagulation for patients with atrial fibrillation (AF). However, evidence of its safety and efficacy is lacking.

The Left Atrial Appendage Occlusion Study II (LAAOS II) explored the feasibility of a definitive trial of LAA occlusion for stroke prevention in AF.

We compared the efficacy of LAA exclusion (during cardiac surgery) and aspirin therapy versus best medical therapy as per guidelines in reducing risk of stroke in AF patients undergoing cardiac surgery.

We concluded that LAA occlusion can be safely performed at the time of cardiac surgery.

A large trial to evaluate the clinical efficacy of LAA occlusion in patients undergoing cardiac surgery is possible in motivated centres, with some modifications to the design of LAAOS II.

Study Type

Interventional - Procedure

Study Design

Open label, multicenter, RCT

NO. of Countries


NO. of Sites


NO. of Participants


Study Period

2009 - 2012



McMaster Surgical Associates (MSA)


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