Relationship Between Catheter Stability And 12-Month Success After Pulmonary Vein Isolation: A Subanalysis of the SMART-AF Trial

Objectives: This study sought to assess the correlation between catheter and tissue contact force (CF) stability and 12-month clinical success for atrial fibrillation (AF) ablation.

Background: The SMART-AF (Thermocool Smarttouch Catheter for the Treatment of Symptomatic Paroxysmal Atrial Fibrillation) multicenter trial provided a robust dataset of AF ablation procedures, using the CF sensing ablation catheter.

Methods: CF and CF stability were correlated with 12-month success for drug-refractory symptomatic AF ablation. CF stability was assessed by stability of ablation parameters (CF, time, location stability) over 3-dimensional electroanatomic maps of pulmonary veins (PVs) using a new proprietary software module and the percentage of time within investigator-selected CF ranges. Available data for potential "PV gaps" were retrospectively identified when stability criteria were not met and were correlated with 12-month success.

Results: Average CF categories of 0 to 10, 10 to 20, and >20 g were associated with 12-month success rates of 90%, 70%, and 70%, respectively; thus, higher average CF did not correlate with treatment success. An exploratory univariate analysis showed significantly higher success rates with a CF of 6.5 to 10.3 g than with <6.5 g (odds ratio: 2.95; 95% confidence interval: 1.13 to 7.72; p = 0.028) but a CF >10 g did not improve success. When stable CF was applied ≥73% of the time within the preselected CF range, success improved. A receiver operating characteristic curve analysis revealed that PV gaps exceeding 10.6-mm distance significantly correlated with 12-month failure.

Conclusions: In the SMART-AF trial, CF stability with sufficient CF was most predictive of optimal 12-month success. (Thermocool Smarttouch Catheter for the Treatment of Symptomatic Paroxysmal Atrial Fibrillation [SMART-AF]; NCT01385202).