Abstract 16238: The Prevalence and Clinical Significance of Residual Carina-Left Atrial Conduction after Successful Encircling Pulmonary Veins Isolation for Paroxysmal Atrial Fibrillation -A Pitfall of the Double-Lasso Technique-

Introduction: Pulmonary vein (PV) isolation (PVI) has been demonstrated to be an effective technique for curing atrial fibrillation (AF). Bidirectional conduction block between the PVs and left atrium (LA) is the gold standard to confirm successful PVI. When ipsilateral PVs are encircled for isolation, a Double-Lasso technique is widely used in this PVI procedure. Although recent reports have revealed that PV carina is also arrhythmogenic, it may be impossible to confirm isolation of the PV carina after encircling ipsilateral PVI (EIPVI) with a Double-Lasso technique alone. The purpose of this study was to reveal the incidence and clinical significance of residual PV carina-LA conduction after EIPVI. Methods: We studied 168 consecutive paroxysmal AF patients (age 60.6±11.7 years, 119men) who underwent EIPVI with a Double-Lasso technique from 2006 to 2008. The end point of EIPVI was demonstration of bidirectional conduction block between the PVs and LA. After successful EIPVI, pacing from the PV carina was performed using an ablation catheter to examine the incidence of residual PV carina-LA conduction. Patients were prospectively followed up in outpatient clinic after EIPVI. Results: Even after individual PVs were successfully isolated with EIPVI, carina-LA conduction remained in 65 (38.6%) patients. During a mean follow-up period of 17.7±12.8 months, AF recurred in 37 (22.0%) patients. Multivariate Cox proportional analysis revealed that PV carina-LA conduction after EIPVI as well as larger LA diameter were significant predictors of AF recurrence (HR=1.89, 95%Cl=1.34–2.74, p=0.0003; and HR=1.08/1mm increase, 95%Cl=1.00–1.14, p=0.059, respectively). Conclusions: A residual conduction between the PV carina and LA often occurred after the successful EIPVI with a double Lasso technique, and it was an independent predictor of AF recurrence after EIPVI. Pacing from the PV carina may be an easy and useful method to confirm that successful EIPVI is completely achieved and may be used as a supplement to EIPVI with a double Lasso technique.