Abstract 19121: Averaged Impedance Drop Workflow for Pulmonary Vein Isolation

Abstract

Background: Previous studies demonstrate that averaged impedance drop (AID) is the most accurate predictor of focal atrial RF ablation lesion transmurality when using the TactiFlex™ SE Ablation Catheter in combination with AutoMark in EnSite™ X EP System version 3.0, however data demonstrating successful incorporation of AID into a pulmonary vein isolation workflow is lacking. Objective: We explored use of AID in conjunction with the AutoMark Distance (AMD) tool to create sets of contiguous, transmural atrial lesions in a chronic swine model and to compare results with inter-lesion gap rates from a historical study of a previous generation catheter (TactiCath) using LSI™ guidance. Methods: RSPV isolation and SVC-IVC and RSPV-CIPV lines were performed in swine (n=9) via point-by-point ablation (target contact force 10g). AID targets of 11, 13, and 15% were selected and minimum-maximum duration bounds were employed (30W/15-50s, 40W/8-20s and 50W/5-10s). Inter-lesion distances of 4mm and 5mm were chosen (balanced across RF powers and anatomical targets). After 12±3 days survival, lesion sets were examined using gross pathology and histology. Results: Histological analysis showed gap incidence rates of 4/223 (1.8%) and 9/215 (4.2%) in the right and left atria, respectively. Per-condition results are shown in Figure 1. The target AID was achieved in 339/487 (69.6%) of ablations, with the target AID reached prior to the minimum duration in 89/487 (18.3%) of trials. Collateral effects were observed, including pulmonary artery thrombosis and inflammation/necrosis extending to trachea/bronchus (N=1). Further characterization of these adverse events could potentially guide upper bounds for AID targets. Conclusions: AID guided ablation resulted in a low rate of inter-lesion gaps, overall comparable to historical data. However, safety and efficacy varied by delivery condition and these results may be useful for guiding clinical use.