Left Atrial Appendage Clip During Open Heart Surgery: Clinical Benefits and Considerations

Introduction to LAA Clipping

• The European Society of Cardiology recommends surgical LAA closure as an adjunct to oral anticoagulation in patients with atrial fibrillation undergoing cardiac surgery to prevent ischemic stroke and thromboembolism (Class I, Level B recommendation) 1, 2

Clinical Benefits of LAA Clipping

• The LAAOS III trial demonstrated that surgical LAA occlusion during cardiac surgery reduced the risk of ischemic stroke or systemic embolism (4.8% vs 7.0% in the control group) with a hazard ratio of 0.67 2

Potential Drawbacks and Complications

• Major bleeding can occur during surgical manipulation of the LAA, with the European Heart Journal citing this as a potential risk 3, 4
• Damage to the circumflex coronary artery is a risk due to its proximity to the base of the LAA, as noted by the American College of Cardiology 5
• Incomplete occlusion remains a significant concern, with some surgical techniques showing success rates as low as 23% for suture exclusion and 0% for stapling, according to the American College of Cardiology 5

Post-Procedural Concerns

• Device-related thrombus formation can occur with an incidence of 1.7%-7.2% and is associated with higher risk of ischemic stroke, as reported by the European Heart Journal 1, 2
• Peri-device leaks (0-5 mm) are present in approximately 25% of cases after LAA closure, according to the European Heart Journal 2
• Incomplete LAA occlusion can lead to a paradoxical increase in stroke risk, as thrombus has been identified in approximately 25% of patients with unsuccessful LAA occlusion, as noted by the American College of Cardiology 5

Anticoagulation Considerations

• LAA occlusion does not eliminate the need for anticoagulation in many patients, as the LAA is not the only left atrial region where thrombi can originate, according to the European Heart Journal 3, 4
• The LAAOS III trial showed benefit when LAA occlusion was added to anticoagulation, not as a replacement for it, as reported by the European Heart Journal 2
• Post-procedure antithrombotic treatment may still expose patients to bleeding risks that could be equivalent to those of direct oral anticoagulants, as noted by the European Heart Journal 2

Clinical Application Considerations

• Surgical LAA exclusion techniques show variable success rates depending on the technique used: excision (73% success), suture exclusion (23%), and stapling (0%), according to the American College of Cardiology 5
• The variable anatomy of the LAA can make consistent and complete occlusion technically challenging, as noted by the American College of Cardiology 5

Conclusion on Clinical Utility

• LAA clipping during open heart surgery is most beneficial for patients with atrial fibrillation who are already undergoing cardiac surgery for other indications, as recommended by the European Heart Journal 1, 2
• The procedure should be considered an adjunct to, rather than a replacement for, anticoagulation therapy in most patients, according to the European Heart Journal 3, 2

Clinical Significance of the Left Atrial Appendage in Atrial Fibrillation

Introduction to Left Atrial Appendage

• The left atrial appendage (LAA) is the main site of thrombus formation in patients with atrial fibrillation, responsible for approximately 90% of cardioembolic strokes in non-valvular AF, making it a critical therapeutic target for stroke prevention 6, 7

Thromboembolic Risk Assessment

• LAA size (>34 cm³), morphology (particularly cauliflower shape), number of lobes (≥3), and low-velocity flow are considered risk factors for thrombus formation 7
• Transesophageal echocardiography (TOE) is the most frequently used diagnostic tool for detecting LAA thrombi with sensitivity of 93-100% and specificity of 99% 7
• Advanced imaging with contrast-enhanced cardiac CT and CMR also provide highly diagnostic (99%) detection of LAA thrombi 7

Therapeutic Implications in AF Management

• Surgical closure of the LAA is recommended as an adjunct to oral anticoagulation in patients with AF undergoing cardiac surgery to prevent ischemic stroke and thromboembolism (Class I, Level B recommendation) 8
• Percutaneous LAA occlusion devices (such as WATCHMAN and Amplatzer Cardiac Plug) may provide an alternative to OAC for AF patients at high risk for stroke with contraindications for chronic OAC 6, 9

Limitations and Considerations

• Not all strokes in AF patients are cardioembolic or due to AF, and the LAA is not the only left atrial region where thrombi can originate 9
• Procedural risks of LAA occlusion include stroke, major bleeding, device-related thrombus, pericardial effusion, vascular complications, and death 8
• Device-related thrombi occur with an incidence of 1.7%-7.2% and are associated with higher risk of ischemic stroke 8
• Peri-device leaks (0-5 mm) are present in approximately 25% of cases after LAA closure 8

Clinical Implications Beyond Thromboembolic Risk

• LAA structure and function are key elements for understanding multiple clinical conditions beyond AF, including cardioembolism, heart failure, and mitral valve diseases 10
• LA enlargement and remodeling have become cornerstone diagnostic and prognostic markers in various cardiovascular conditions 10

Imaging Modalities for LAA Assessment

• Transesophageal echocardiography remains the gold standard for LAA thrombus detection 7
• Ultrasound contrast agents improve the diagnostic accuracy of TOE for detecting thrombi 7
• Cardiac CT and CMR with dedicated protocols are highly accurate alternatives for LAA thrombus detection 7
• 3D imaging techniques provide enhanced visualization of LAA anatomy and are particularly useful for pre-procedural planning of LAA closure 7

Left Atrial Appendage Closure Techniques

Device Selection and Technical Approach

• The European Society of Cardiology recommends percutaneous LAA closure using either the WATCHMAN or Amplatzer Amulet device via transseptal approach for patients with atrial fibrillation at high stroke risk who have contraindications to long-term anticoagulation, with both devices demonstrating comparable safety and efficacy 11, 12
• The WATCHMAN device and Amplatzer Amulet are the two primary self-expanding devices placed trans-septally in the LAA and have the most robust clinical evidence 11, 12

Procedural Requirements and Learning Curve

• A significant learning curve exists for LAA closure, with serious pericardial effusions occurring in 7.1% of the first 3 implant patients at each site compared to 4.4% of subsequent patients 13
• The American College of Cardiology recommends that new implanters can achieve success and complication rates comparable to experienced operators when proper training protocols are followed 14

Patient Selection and Indications

• The European Society of Cardiology gives a Class IIb recommendation for percutaneous LAA closure only for patients with absolute contraindications to long-term oral anticoagulation 11, 12
• The American Heart Association recommends surgical LAA closure during cardiac surgery as adjunctive therapy to anticoagulation, with a Class I, Level B recommendation 11, 12