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Left Atrial Appendage Triggers in Atrial Fibrillation
Study Questions:
How often is atrial fibrillation (AF) triggered by premature depolarizations arising in the left atrial appendage (LAA)?
Methods:
This was a retrospective analysis of 7,129 patients who underwent AF ablation. After pulmonary vein (PV) isolation, a stimulation protocol was performed to provoke non-PV triggers. Four catheters were positioned at various locations in the atria. Triggers were provoked by isoproterenol or by cardioversion to induce immediate recurrences of AF.
Results:
The LAA was a source of triggers in 21 patients (0.3%). Twenty of the 21 patients were undergoing a redo ablation procedure. The LAA was the only source of triggers in 3 of 21 patients. In the other 18 patients, other trigger sites most commonly were the mitral annulus, left atrial roof, and coronary sinus. The LAA triggers were eliminated by focal ablation (19 patients) or LAA isolation (two patients). Other triggers were eliminated by focal ablation. After a mean of 5 years of follow-up, 38% of patients with LAA triggers were arrhythmia-free. One of two patients who underwent LAA isolation developed a LAA thrombus despite anticoagulation.
Conclusions:
The LAA is rarely the source of AF triggers and recurrent atrial arrhythmias are common after elimination of the LAA triggers.
Perspective:
Prior cohort studies have generally reported that LAA isolation improves the outcome of AF ablation in patients undergoing redo ablation for persistent AF. In a randomized study (BELIEF trial), patients with longstanding persistent AF who underwent first-time extensive ablation plus LAA isolation were approximately twice as likely to remain arrhythmia-free than patients who underwent extensive ablation without LAA isolation. However, there have been concerning reports that LAA isolation is associated with a heightened risk of LAA thrombus, even in patients who are anticoagulated. The current study makes the case for the selective use of LAA isolation and suggests that LAA triggers usually can be eliminated by focal ablation, obviating the need for LAA isolation. However, if LAA triggers truly are as infrequent as reported in the current study, the results of the BELIEF trial would suggest that LAA isolation is clinically helpful by some mechanism other than trigger elimination.
Clinical Topics: Anticoagulation Management, Arrhythmias and Clinical EP, Anticoagulation Management and Atrial Fibrillation, Implantable Devices, EP Basic Science, SCD/Ventricular Arrhythmias, Atrial Fibrillation/Supraventricular Arrhythmias
Keywords: Arrhythmias, Cardiac, Anticoagulants, Atrial Appendage, Atrial Fibrillation, Catheter Ablation, Coronary Sinus, Electric Countershock, Heart Atria, Isoproterenol, Pulmonary Veins, Recurrence, Thrombosis
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