The spatio-temporal behavior of atrial electrogram fractionation in persistent Atrial Fibrillation

The temporal behavior of atrial electrograms (AEGs) during persistent atrial fibrillation (persAF) remains poorly understood. In the present work, we investigated the temporal behavior of consecutive AEGs and the consistency of complex fractionated atrial electrograms (CFAEs) with the CARTO (Biosense Webster) criterion. 797 bipolar AEGs were exported from NavX (St. Jude Medical) with three segment lengths (2.5 s, 5 s and 8 s) from 18 patients undergoing persAF ablation. Three 2.5 s consecutive segments were created from the 8 s AEGs. CFAE classification was applied offline to all cases following the CARTO criterion. CFAEs were defined as AEGs with the interval confidence level (ICL) ≥4. Moderate correlation was found in AEG classification between the consecutive segments (segment 1 vs 2: Spearman’s correlation ρ=0.74, Kappa score κ=0.62; segment 1 vs 3: ρ=0.72; κ=0.62; segment 2 vs 3: ρ=0.75; κ=0.68), resulting in different CFAE maps. AEGs with 5 s generated AEG classification more similar to 8 s (ρ=0.96; κ=0.87) than 2.5 s vs 5 s (ρ=0.93; κ=0.84) and 2.5 s vs 8 s (ρ=0.90; κ=0.78). The results suggest that consecutive 2.5 s AEGs resulted in different ablation target identification, which would affect the ablation strategy and contribute to the conflicting outcomes in AEG-guided ablation of persAF. CARTO criterion should be revisited in clinic and consider AEGs with longer duration for consistent CFAE classification in persAF.