What are the guidelines for Left Atrial Appendage (LAA) exclusion in patients with atrial fibrillation?

Left Atrial Appendage Exclusion in Atrial Fibrillation

Surgical LAA exclusion should be performed in patients with AF undergoing cardiac surgery for another indication, as it reduces stroke risk by 33% when added to anticoagulation, based on the landmark LAAOS III trial. 1

Surgical LAA Exclusion

Primary Indication

• Surgical LAA occlusion is recommended as adjunctive therapy during concomitant cardiac surgery in patients with AF to reduce thromboembolic risk, regardless of whether they continue anticoagulation postoperatively. 1
• The LAAOS III trial demonstrated that surgical LAA occlusion at the time of cardiac surgery reduced ischemic stroke or systemic embolism from 7.0% to 4.8% over 3.8 years (HR 0.67,95% CI 0.53-0.85, P=0.001). 1
• This benefit occurred despite 77% of patients continuing oral anticoagulation, establishing surgical LAA closure as an adjunct rather than replacement for anticoagulation. 1

Technical Considerations and Success Rates

• Excision techniques achieve 73% success rates compared to only 23% for suture exclusion and 0% for stapling alone, making excision the preferred surgical approach. 1
• Incomplete occlusion occurs in approximately 50-60% of cases overall, with persistent flow or remnant stumps >1.0 cm. 1
• Thrombus formation occurs in 25% of patients with unsuccessful LAA occlusion, necessitating continued anticoagulation regardless of attempted surgical closure. 1
• The circumflex coronary artery's proximity to the LAA base limits aggressive closure techniques due to injury risk. 1

Standalone Surgical Approaches

• For patients not undergoing other cardiac surgery, the 2014 AHA/ACC/HRS guidelines provide only a Class IIb recommendation ("may be considered"), reflecting limited evidence at that time. 1
• Totally thoracoscopic approaches using clipping systems show promise with high acute success rates (>90%) and minimal procedural times (20-40 minutes). 2

Percutaneous LAA Occlusion

Current Guideline Recommendations

• Percutaneous LAAO may be considered (Class IIb) only in patients with absolute contraindications to long-term oral anticoagulation. 1, 3
• The 2024 ESC guidelines emphasize that with DOACs showing similar bleeding rates to aspirin, the role of percutaneous LAAO in current practice remains unclear. 1
• The 2018 CHEST guidelines suggest LAAO for patients at high risk of ischemic stroke with absolute contraindications to oral anticoagulation (weak recommendation, low quality evidence). 1, 3

Evidence Base and Limitations

• No randomized trials compare LAAO devices with DOACs, only with warfarin, which is no longer standard of care. 1, 3
• Five-year data from Watchman trials showed similar composite endpoints versus warfarin, with lower hemorrhagic stroke and all-cause death but a 71% non-significant increase in ischemic stroke. 1
• The PRAGUE-17 trial demonstrated non-inferiority of LAAO versus DOACs for broad composite endpoints, though larger trials are needed. 1

Procedural Risks

• Serious periprocedural complications occur in 6-7% of cases, including device embolization, major bleeding, pericardial effusion requiring drainage, and LAA perforation. 3, 4, 5
• Device-related thrombus formation occurs in up to 7.2% per year and associates with increased ischemic stroke risk during follow-up. 3
• A learning curve exists with higher complication rates in initial cases at each center. 3

Post-Procedural Antithrombotic Therapy Paradox

• The requirement for post-procedural anticoagulation (warfarin for 45 days) or dual antiplatelet therapy (DAPT for 6 months) exposes patients to bleeding risks potentially equivalent to DOACs, creating a paradox for patients who received the device due to bleeding contraindications. 3
• Standard protocol includes: Phase 1 (0-45 days) warfarin plus aspirin, Phase 2 (45 days-6 months) DAPT with aspirin and clopidogrel, Phase 3 (>6 months) aspirin monotherapy indefinitely. 3

Device-Specific Considerations

• The Lariat device uses an epicardial snare approach but shows incomplete occlusion in approximately 20% of cases with inexperienced operators. 3, 4, 5
• Acute procedural success with Lariat ranges from 92-100%, though complications include pericarditis (common), pericardial effusion, and rare LAA perforation. 4, 5

Critical Clinical Pitfalls

Incomplete surgical LAA occlusion is common and dangerous - approximately 50% of surgical attempts fail to achieve complete occlusion, and these patients have significantly higher thromboembolic event rates. 1 Therefore:

• Continue anticoagulation in all patients after attempted surgical LAA closure unless complete occlusion is confirmed by TEE. 1
• Obtain follow-up TEE at 45 days to verify complete closure (no flow, no remnant >1.0 cm). 1

Oral anticoagulation remains first-line therapy - percutaneous LAAO should not be considered an equivalent alternative to anticoagulation but rather a last resort for patients with true absolute contraindications. 1, 3