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Updated: May 3, 2026
Catheter Ablation in Combination With Left Atrial Appendage Closure for Atrial Fibrillation
Published on: February 26, 2013
Rationale and design of the Left Atrial Appendage Occlusion Study (LAAOS) III
Richard Whitlock1, Jeff Healey2, Jessica Vincent3
1Department of Surgery, McMaster University, Hamilton, Canada ; ; Population Health Research Institute, McMaster University and Hamilton Health Sciences, Hamilton, Canada ;
Insights
Left atrial appendage occlusion (LAAO) is being studied for stroke prevention in atrial fibrillation (AF) patients undergoing cardiac surgery. The LAAOS III trial will determine its safety and efficacy in reducing stroke risk.
Area of Science:
- Cardiology
- Neurology
- Surgical Innovation
Background:
- Left atrial appendage (LAA) occlusion is a potential stroke prevention strategy for patients with atrial fibrillation (AF).
- Current evidence regarding the efficacy and safety of LAA occlusion is limited.
- The LAAOS III trial is designed to definitively assess LAA occlusion in cardiac surgical patients with AF.
Purpose of the Study:
- To evaluate the efficacy of LAA occlusion in preventing stroke and systemic arterial embolism in patients with AF undergoing cardiac surgery.
- To assess the safety and various clinical outcomes associated with LAA occlusion during cardiac surgery.
Main Methods:
- Randomized trial involving 4,700 patients with AF scheduled for on-pump cardiac surgery.
- Patients will be randomized to either LAA occlusion or no LAA occlusion.
- Primary outcome: first occurrence of stroke or systemic arterial embolism over a 4-year follow-up. Secondary outcomes include mortality, operative safety, re-hospitalization for heart failure, major bleeding, and myocardial infarction.
Main Results:
- The Left Atrial Appendage Occlusion Study (LAAOS) III is currently in its vanguard phase.
- As of September 9, 2013, 162 patients have been recruited.
- The study is funded by the Canadian Institutes for Health Research (CIHR), the Canadian Network and Centre for Trials Internationally, and McMaster University Surgical Associates.
Conclusions:
- LAAOS III is poised to be the largest trial investigating the efficacy of LAA occlusion for stroke prevention in AF.
- The study's findings are expected to enhance understanding of stroke mechanisms in AF.
- Results will clarify the safety and efficacy of surgical LAA occlusion as a therapeutic option.
Background:
Occlusion of the left atrial appendage (LAA) is a promising approach to stroke prevention in atrial fibrillation (AF). However, evidence of its efficacy and safety to date is lacking. We herein describe the rationale and design of a definitive LAA occlusion trial in cardiac surgical patients with AF.
Methods:
We plan to randomize 4,700 patients with AF in whom on-pump cardiac surgical procedure is planned to undergo LAA occlusion or no LAA occlusion. The primary outcome is the first occurrence of stroke or systemic arterial embolism over a mean follow-up of four years. Other outcomes include total mortality, operative safety outcomes (chest tube output in the first post-operative 24 hours, rate of post-operative re-exploration for bleeding in the first 48 hours post-surgery and 30-day mortality), re-hospitalization for heart failure, major bleed, and myocardial infarction.
Results:
Left Atrial Appendage Occlusion Study (LAAOS) III is funded in a vanguard phase by the Canadian Institutes for Health Research (CIHR), the Canadian Network and Centre for Trials Internationally, and the McMaster University Surgical Associates. As of September 9, 2013, 162 patients have been recruited into the study.
Conclusions:
LAAOS III will be the largest trial to explore the efficacy of LAA occlusion for stroke prevention. Its results will lead to a better understanding of stroke in AF and the safety and efficacy of surgical LAA occlusion.
