B-PO05-098 LOCAL IMPEDANCE CHARACTERISTICS OF PULMONARY VEIN RECONNECTIONS DURING REPEATED ATRIAL FIBRILLATION ABLATION PROCEDURES: INSIGHT FROM AN ITALIAN MULTICENTER REGISTRY

Abstract

AF recurrence is highly associated with pulmonary vein (PV) reconnection. Limited data exist on PV gaps characterized by Local Impedance (LI). to characterize PV gaps and ablated tissue with a novel LI algorithm after repeated AF ablation procedures according to previous ablation strategy. Consecutive patients (pts) undergoing redo AF ablation from the CHARISMA registry at 6 Italian centers were included. Rhythmia mapping system was used to map the left atrium and PVs before and after ablation. LI characteristics were collected through a RF ablation catheter equipped with a dedicated LI algorithm (DirectSense). Each gap was characterized in terms of LI and its variations during the procedure. Ablation endpoint was PVI as assessed by entrance and exit block. A total of 41 PV gaps (mean number of gaps per pt=2.3±1.1) from 18 cases were detected: 20 gaps from 9 cases after RF ablation and 21 gaps from 9 cases after cryoablation. One gap was identified in 5 (28%) pts, 2 gaps in 7 (39%) and >3 gaps in 6 (33%). The mean LI at gap sites was 113.9±15Ω prior to ablation: it was significantly higher than LI at scar tissue closer to gap (99.7±8Ω, p<0.0001) but was significantly lower than LI at healthy tissue (120.2±12Ω, p<0.0001). Distances measurement between lesions previously performed at the roof, at the inferior and posterior wall were 53±22 mm, 44±19mm and 43±18mm, respectively, and were similar between previous ablation strategy (p=0.7449, p=0.9251 and p=0.8028). LI parameters did not differ between prior ablation approach (RF vs Cryo: 115.5±13Ω vs 112.2±16Ω for LI at gap, p=0.4739; 102.2±6Ω vs 97.3±10Ω LI at scar tissue, p=0.0591; 16.4±4Ω vs 15.8±13Ω for LI drop at gap, p=0.6647). In 14 cases (34.1%) the difference between LI at healthy tissue and LI at gap was lower than 5Ω, suggesting that this spot was not treated by RF or Cryo delivery in the previous ablation (13 out 21 after Cryo ablation vs 1 out 20 after RF ablation, p<0.0001). No complications during the procedures were reported. All PVs were successfully isolated in all study pts. LI characteristics at PV gaps significantly differ from both scar and healthy tissue. No significant difference was recorded between prior ablation approaches in terms of lesion extension.