Abstract 18101: EFFICAS I Results - Are Low Contact Force Parameters Predictors for Gap Formation after Pulmonary Vein Isolation by Radiofrequency Catheter Ablation?

Abstract

Objectives Electrical reconnection of pulmonary veins (PVs) results in recurrences of atrial fibrillation (AF) following PV isolation (PVI). Gaps in the isolation lines may occur due to suboptimal catheter tip-to-tissue contact force (CF) during ablation. EFFICAS I, a multi-center prospective study, evaluated the relationship between CF parameters and gap formation during follow-up. Methods Pts with paroxysmal AF underwent PVI using an irrigated RF ablation catheter that provides tip-to-tissue CF information (TactiCath®, Endosense, Switzerland). The operator was blinded to the CF, but CF and Force Time Integral (FTI) were recorded for later analysis. PV antra were divided into 8 segments of interest (SEG). Patients underwent a re-mapping procedure at 3 months to evaluate gap occurrence. Incidence of gaps per SEG at 3 months was correlated with CF and FTI during initial PVI. Results Forty pts (59 ± 10 yrs, 30 males) were treated by 10 operators at 3 centers with 2519 RF ablations. Average CF at the right PVs was higher compared to the left PVs (26.0 ± 16.6 g vs. 17.9 ± 13.0 g, p<0.0001). Greater CF was applied to the posterior wall than the left anterior wall (21.9 ± 14.5 g vs. 13.3 ± 9.9 g, p<0.0001). At re-mapping, 26 pts (65%), including 6 pts (15%) with AF recurrence, had 52 gaps out of 318 SEGs (gap ratio 16%). CF was lower in the SEGs with gaps compared to no-gap SEGs (19.5 ± 14.4 g vs. 22.4 ± 14.8 g, p=0.04), but the strongest gap predictor was the minimum FTI applied at each SEG with 213 ± 325 gs for gap vs 434 ± 599 gs for no-gap SEGs (p<0.001). Likelihood for gap considerably increased with minimum FTI < 400 gs (21% vs 5%, p<0.001, Odd Ratio = 4.8) with a significant inverse relationship between minimum FTI and incidence of gaps (Figure). Conclusions Low minimum FTI, as an indicator of catheter stability, is a strong predictor of gap occurrence following previous PVI. This endpoint also correlates with low CF. Optimization of minimum FTI threshold will be determined in ongoing EFFICAS II study.