Atrial fibrillation driver identification through regional mutual information networks: a modeling perspective.

PURPOSE: Effective identification of electrical drivers within remodeled tissue is a key for improving ablation treatment for atrial fibrillation. We have developed a mutual information, graph-based approach to identify and propose fault tolerance metric of local efficiency as a distinguishing feature of rotational activation and remodeled atrial tissue. METHODS: Voltage data were extracted from atrial tissue simulations (2D Karma, 3D physiological, and the Multiscale Cardiac Simulation Framework (MSCSF)) using multi-spline open and parallel regional mapping catheter geometries. Graphs were generated based on varied mutual information thresholds between electrode pairs and the local efficiency for each graph was calculated. RESULTS: High-resolution mapping catheter geometries can distinguish between rotational and irregular activation patterns using the derivative of local efficiency as a function of increasing mutual information threshold. The derivative is decreased for rotational activation patterns comparing to irregular activations in both a simplified 2D model (0.0017 ± 1 × 10-4 vs. 0.0032 ± 1 × 10-4, p < 0.01) and a more realistic 3D model (0.00092 ± 5 × 10-5 vs. 0.0014 ± 4 × 10-5, p < 0.01). Average local efficiency derivative can also distinguish between degrees of remodeling. Simulations using the MSCSF model, with 10 vs. 90% remodeling, display distinct derivatives in the grid design parallel spline catheter configuration (0.0015 ± 5 × 10-5 vs. 0.0019 ± 6 × 10-5, p < 0.01) and the flower shaped open spline configuration (0.0011 ± 5 × 10-5 vs. 0.0016 ± 4 × 10-5, p < 0.01). CONCLUSION: A decreased derivative of local efficiency characterizes rotational activation and varies with atrial remodeling. This suggests a distinct communication pattern in cardiac rotational activation detectable via high-resolution regional mapping and could enable identification of electrical drivers for targeted ablation.

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).