Deterministic structures in fractionated atrial electrograms during human persistent atrial fibrillation

In the present work, we sought to uncover possible deterministic dynamics in atrial tissue activations during persistent atrial fibrillation (persAF) using recurrence plots (RP) and recurrence quantification analysis (RQA). 797 bipolar atrial electrograms (AEGs) were collected from 18 persAF patients undergoing pulmonary vein isolation (PVI). Automated AEG classification was performed using the CARTO criteria (Biosense Webster). Four RQA attributes were obtained from the AEGs: determinism (DET); the recurrence rate (RR); the laminarity (LAM); and the Shannon entropy of the diagonal line in a RP (ENTR). PVI significantly increased the four RQA features ([Mean±SD], DET: 87.7±8.3% vs. 90.7±8.5%; RR: 60.2±17.3% vs. 63.6±17.4%; LAM: 93.9±4.7% vs. 95.3±5.5%; ENTR: 3.9±0.6 vs. 4.2±0.8, P≤0.0001). The attributes were higher for normal AEGs (normal vs. fractionated, DET: 90.5±8.7% vs. 86.7±7.6%; RR: 64.0±18.0% vs. 57.9±15.6%; LAM: 95.1±5.5% vs. 93.5±4.1%; ENTR: 4.2±0.8 vs. 3.8±0.5, P≤0.0001). Our results suggest that the increase of irregular activations on fractionated AEGs in persAF was not associated to a random structure. Diagonal structures associated to deterministic behaviour were still present in RPs from fractionated AEGs, leading to a high residual determinism, which could be related to unstable periodic orbits in a chaotic motion.