Abstract 3316: A New Approach for Complete Isolation of the Posterior Left Atrium Including Pulmonary Veins (Box Isolation) for Atrial Fibrillation
Background: Pulmonary vein (PV) isolation with continuous circular lesions around the ipsilateral PVs has been widely performed to cure atrial fibrillation (AF). However, esophageal injury is a potential complication after catheter ablation of the posterior aspect of the left atrium (LA). Therefore, we describe a new approach for complete isolation of the posterior LA including all PVs, namely Box isolation, to avoid the esophageal injury.
Methods and Results: Forty six patients (59±10 years, 4 women) with symptomatic paroxysmal AF underwent Box isolation guided by double Lasso technique. Continuous lesions at the anterior portions of the ipsilateral superior and inferior PVs was initially created and subsequently linear ablation joining the 2 superior PVs (roof line) and the 2 inferior PVs (bottom line) was performed to isolate the posterior LA. Continuous lesions at the posterior portions of PVs along the esophageal aspect of the posterior LA were not created. Ablation was performed with an 8 mm tip catheter with temperature and power limited to 50°C and 30 – 40W. The endpoint was the absence of electrical activity and the inability to pace the posterior LA and all PVs in sinus rhythm. Complete isolation of posterior LA was achieved in 41 patients (89%) with 60±21 minutes of RF energy. Fluoroscopic and procedural times were 68±15 and 182±47 minutes. Ablation resulted in termination of AF in 75% (18/24), and subsequent noninducibility of AF in 91% (42/46) of the patients. However, atrial tachycardia could be induced in 10 patients (22%) after ablation. A repeat ablation was performed in 3 of 6 patients with recurrence of arrhythmia. During the repeat study, recovered conduction gaps were found in all patients and successfully closed with segmental ablation. At 6±2 months follow-up, 43 patients (93%) were arrhythmia free without antiarrhythmic drugs and the remaining patients were arrhythmia free requiring drugs. No complications occurred.
Conclusions: This study demonstrates the feasibility of effectively achieving complete isolation of the posterior LA including all PVs without lesions of the esophageal aspect of the posterior LA. The Box isolation is associated with a high clinical success rate and a low risk of the esophageal injury.