Introduction: Esophageal injury is a potential complication after catheter ablation of the posterior left atrium (LA). Therefore, we describe a new approach for complete isolation of the posterior LA including all pulmonary veins (PVs) without vertical lesions along the esophageal aspect of the posterior LA, namely Box isolation.
Methods and Results: Ninety-one patients with paroxysmal atrial fibrillation (AF) underwent Box isolation. Continuous lesions at the anterior portions of the ipsilateral PVs were initially created and then linear ablation of LA roof and bottom was performed to isolate the posterior LA. Continuous vertical 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. 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 the posterior LA was achieved in 82 patients (90%). Ablation resulted in the termination of AF in 65%, and subsequent noninducibility of AF in 71% of the patients. A repeat ablation was performed in six of nine patients with recurrence of arrhythmia. At 13 ± 3 months of follow-up, 86 patients (95%) were arrhythmia-free without antiarrhythmic drugs.
Conclusion: This study shows that it is possible to achieve complete isolation of the posterior LA including all PVs without posterior vertical lesions. Box isolation is associated with a high clinical success rate.