Multidetector computed tomography-derived left atrial wall thickness maps of patients undergoing persistent atrial fibrillation ablation

FUNDING ACKNOWLEDGEMENTS: Type of funding sources: None. BACKGROUND: Pulmonary vein isolation (PVI) has proven to be effective in treating persistent atrial fibrillation (PeAF), although long-term ablation outcomes have been significantly less favorable than in paroxysmal AF. PURPOSE: We sought to analyze multidetector computed tomography (MDCT)-derived left atrial wall thickness (LAWT) maps of patients undergoing PeAF radiofrequency ablation with a personalized approach aimed for adapting the ablation index (AI) of contiguous lesions to the local LAWT. METHODS: PeAF was defined in the presence of at least one AF episode sustained beyond 7 days, long-standing PeAF was defined as continuous AF of >12 months duration when decided to adopt a rhythm control strategy. For each patient included in the analysis, LAWT three-dimensional map were obtained from MDCT. LAWT was categorized into 1 mm layers and AI was titrated according to the LAWT. RESULTS: One hundred twenty-one patients (79.4% male, age 64.5±9.5 years) were included. Procedure time was 67 minutes (IQR 50-67), fluoroscopy time was 43 seconds (IQR 20-71), and radiofrequency time was 16.5 minutes (IQR 14.3-18.4). LAWT of the circumferential PV line was thicker in the LPVs as compared to the RPVs (1.64 mm [1.5-1.81] vs. 1.29 mm [1.16-1.57], p<0.01). More specifically, anterior wall segments were thicker in the LPVs as compared to the RPVs (2.1 mm [1.9-2.4] vs. 1.4 mm [1.1-1.9], p<0.01), while posterior wall segments had similar WT. Ablation index applied according to local LAWT was 387 (IQR 360-410) for the anterior wall and 335 (IQR 300-375) for the posterior wall. Overall first pass rate was 73.6%; median LAWT values were higher for PVs with no first pass during radiofrequency ablation with respect to the whole cohort (1.73 mm [1.57-1.98] vs. 1.64 mm [1.50-1.81] p=0.02 for LPVs; 1.46 mm [1.21-1.65] vs. 1.29 mm [1.16-1.57] p=0.03, for RPVs). LAWT values for each PV segment are represented in Figure 1. At a 12 months of follow-up the rate of recurrence-free survival was 79%. Recurrence-free survival rate was significantly higher in patients with PeAF with respect to those with long-standing PeAF diagnosis (p=0.044). A second ablation was performed in 18 patients out of those with AT/AF recurrence. Median LAWT values were higher for PVs with reconnection found in the redo procedures comparing to the median LAWT of the corresponding PVs of the whole cohort (1.77 mm [1.65-2.14] vs. 1.64 mm [1.50-1.81] p=0.01 for LPVs; 1.43 mm [1.25-1.61] vs. 1.29 mm [1.16-1.57] p=0.05, for RPVs). Methods and results are summarized in Figure 2. CONCLUSION: This proof-of-concept study proves that personalized local LAWT-guided PVI ablation for PeAF is efficient and have good long-term outcomes. No first-pass segments during first procedure and reconnection sites within redo procedures were mostly found in thickest regions. A randomized trial comparing the LAWT-guided PVI with the standard of practice is in progress. [Figure: see text] [Figure: see text]