Contact-force local impedance algorithm to guide effective pulmonary vein isolation inAF patients: 1-year outcome from an international multicenter clinical setting

Abstract Background The combination of highly localized impedance (LI) and contact force (CF) may improve tissue characterization and lesion prediction during radiofrequency (RF) pulmonary vein isolation (PVI) in patients with atrial fibrillation (AF). Objective We report the outcomes of our acute and long-term clinical evaluation of CF-LI guided PVI in consecutive AF ablation cases from an international multicenter clinical setting. Methods Consecutive patients (pts) from 16 European centers undergoing de novo AF RF catheter ablation with the Stablepoint catheter endowed of CF and LI measurement capabilities were enrolled in the CHARISMA registry. Ablation was guided by the magnitude and time-course of LI drop during RF delivery. The maximum distance between each ablation spot (center-to-center) was suggested to be ≤6 mm. Procedural endpoint was the achievement of the PVI as assessed by entrance and exit block. Post-ablation, all patients were monitored with ambulatory event monitoring. Additional ECG monitoring was performed as indicated by patient symptoms. Data are reported as mean±SD. Results From a total of 212 consecutive pts, 151 were followed-up for at least 12 months after the procedure and were included in this 1-year outcome analysis (61.6% paroxysmal AF, 38.4% persistent AF, 78.8% de novo procedures, 21.2% redo procedures). Baseline LI was 161.2±19 Ω with LI drop of 21.9±9 Ω (LI drop rate=3.1±2 Ω/s). The first pass isolation rate per vein was 93.3%. LI drop was predicted by baseline LI (r=0.56, 95%CI:0.55 to 0.57, p<0.0001). Effective ablation spots showed both higher baseline LI and LI drop compared with 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). No steam pops or complications, including atrio-esophageal fistula or tamponade were reported during or after the procedures. At the end of the procedures all PVs were successfully isolated in all study patients. During a median follow-up of 377 [365 – 402] days, 11 (7.3%) patients experienced an early recurrence of AF during the 90-day blanking period. Overall, 21 pts (13.9%) suffered an AF recurrence after the 90-days blanking period (10.8% with paroxysmal AF vs 19% with persistent AF, p=0.226; 10.9% for de novo procedures vs 25.0% for redo procedures, p=0.079). De novo paroxysmal AF pts showed the lowest rate of recurrence (5 out 69 pts, 7.2%). The time to recurrence was comparable among AF type (HR=1.73; 0.73 to 4.05; p=0.210 for persistent vs paroxysmal AF) whereas was shorter in repeated AF ablation procedures (HR=2.49; 1.04 to 5.98; p=0.042 for redo vs de novo procedure). Early recurrence was not associated with late recurrence (HR=2.29; 0.68 to 7.76; p=0.182). Conclusions In our experience, the magnitude of LI drop is predictive of PV segment isolation. An ablation strategy for PVI guided by CF-LI technology was safe and effective, and resulted in a low recurrence rate of AF at 1-year follow-up irrespective of underlying AF type.