Cardiac CT With Delayed Enhancement in the Characterization of Atrial Arrhythmias Structural Substrate: Relationship Between CT-Segmented Scar and Electro-Anatomic Mapping

BACKGROUND: Pulmonary vein isolation (PVI) is the cornerstone of catheter-based strategies for AF ablation and has proven to be effective in treating paroxysmal atrial fibrillation (PAF). PVs reconnection after AF ablation is the main cause of AF recurrence and results from non-contiguous or non-transmural RF lesions as the consequence of insufficient RF delivery in the thickest myocardial areas. Similarly, excessive RF delivery in thin regions of the left atrial (LA) wall is associated to increased complication rate. Multidetector computed tomography (MDCT) have been reliably validated to assess left atrial wall thickness (LAWT). AIMS: To determine if adapting radiofrequency (RF) to the left atrial wall thickness (LAWT) is feasible, effective, and safe during paroxysmal atrial fibrillation (PAF) ablation in comparison with the standard approach. METHODS AND RESULTS: Consecutive patients referred for PAF first ablation were prospectively enrolled and divided into 2 groups, the LAWT-Group and the No-LAWT (i.e. control) Group. The LAWT three-dimensional maps were obtained from pre-procedure multidetector computed tomography and integrated into the navigation system. Ablation index was titrated according to the local LAWT, and the ablation line was personalized to avoid the thickest regions while encircling the PV antrum. A total of 39 patients (79% male, age 60 ± 9.5 years) were included. LAWT Group showed a significantly shorter procedural time (101±30 vs 133±38 min, p=0.007), fluoroscopy time (6.7±3,4 vs 12±0.4, p=0,02) and a trend for a lower radiation dose (3.8±3.1 vs 6.3±4.9 Gy/cm2, p= 0.06), with a comparable radiofrequency (13±1.7 vs 15±7.4 min, p=NS) time. Radiofrequency power used posteriorly resulted significantly inferior to the anterior one (37±2.5 vs 53±19 watts, p<0,001). Right PVs showed a significantly lower tailored AI (382±13 vs 433±35, p<0,001), while for left PV AI resulted comparable between groups (397±22 vs 409± 105, p=NS). LAWT groups showed 100% of first pass PV isolation and no recurrences during 12 months follow-up, while No-LAWT patients experiences 2 no first pass (10%) and 2 AA recurrences (10%) at 1 year. CONCLUSIONS: Personalized AF ablation with the Ablate-By-LAWT protocol using a single catheter technique and adapting the AI to LAWT is feasible and more effective than the conventional approach, with a comparable safety.