Local impedance technology for effective PVI with a novel ablation catheter: results from a large, international, multicenter registry

FUNDING ACKNOWLEDGEMENTS: Type of funding sources: None. BACKGROUND: Highly localized impedance (LI) measurements in combination with a catheter-tissue contact force (CF) during atrial fibrillation (AF) ablation may improve tissue characterization and lesion prediction during pulmonary vein isolation (PVI). PURPOSE: This analysis explores the relationship between LI parameters, ablation spot locations and procedural success during ablation of PVs in a large population of consecutive AF patients. METHODS: Two-hundred twelve consecutive patients from 16 European centers undergoing de novo AF radiofrequency (RF) catheter ablation with a novel open-irrigated tip catheter enabled by CF and LI measurement capabilities (Stablepoint) were included. Ablation was guided by the magnitude and time-course of LI drop during RF delivery. The interlesion distance between each ablation spot was set ≤6 mm. First pass isolation (FPI) was defined as successful PVI at or before completion of the first encircling lesion set regardless of visual gaps. Procedural endpoint was the achievement of the PVI as assessed by entrance and exit block. Data are reported as mean±SD. RESULTS: A total of 13891 ablation spots performed around PVs were analyzed (baseline LI=161.2±19 Ω; LI drop=21.9±9 Ω; LI drop rate=3.1±2 Ω/s; RF Delivery time=9.2±4 s; CF=12.5±7 g). LI drop was predicted by baseline LI (r=0.56, 95%CI:0.55 to 0.57, p<0.0001). A total of 80 PV gaps were detected, mostly at the right pairs of the PV (63.7%, p=0.013). The FPI rate per vein was 93.3% resulting from 180 patients (84.9%) with FPI. PV gaps were located at anterior (31.3%), posterior (31%), and carina (16%) sites after the FPI evaluation. At successful ablation spots, both baseline LI and LI drop were larger than at PV gap spots (161.4Ω vs 153.0Ω, p<0.0001 for baseline LI; 22.1Ω vs 14.4Ω, p<0.0001 for LI drop), whereas RF delivery time was shorter (9.1s at successful ablation spots vs 10.1s at PV gap spots, p<0.0001). CF values seem to be higher at successful ablation spot that at PV gap spots (12.5g vs 11.4g, p=0.0592). On the basis of the receiver-operating characteristic curve (ROC) analysis, the best LI drop that predicts successful ablation spots was >20Ω (Sensitivity=56.8%, Specificity=93.2%, PPV=99.7%, Area under the ROC curve=0.7841, p<0.0001). Optimal LI drops were identified by left atrial region and were >21Ω at anterior sites and >18Ω at posterior sites. No steam pops or complications were reported during the procedures. All PVs were successfully isolated in all study patients CONCLUSIONS: In a large, international population of consecutive de novo AF cases, an ablation strategy guided by LI and CF information results in a very high first pass isolation rate. LI drop is predictive of PV segment isolation. A regional approach to RF ablation guided by LI information may be useful in patients with AF.