Spatiotemporal organization during ablation of persistent atrial fibrillation.

BACKGROUND Targeting complex fractionated atrial electrograms improves the outcome of ablation of persistent atrial fibrillation (AF); however, the mechanism(s) responsible for the generation of complex fractionated atrial electrogram signals and efficacy of ablation is not clear. OBJECTIVE The aim of this study was to gain mechanistic insight into ablation of persistent AF by evaluating the spatiotemporal patterns of atrial organization during ablation. METHODS Intracardiac recordings from 18 ablation procedures were analyzed. Signals recorded by right atrial/coronary sinus catheters were processed. We quantified atrial organization using recurrence maps and recurrence percentage (Rec%) methodology and generated temporally dense time series of cycle lengths and Rec%. RESULTS A total of 162 intra-atrial recordings were categorized into type I (sudden jump in Rec%), type II (gradual increase), and type III (no increase). Type I was the most common form and was seen in 57% ± 4% of the recordings. A typical pattern was the initial appearance of local organization, which then expanded to adjacent channels in discrete jumps until eventually an organized atrial flutter emerged. This pattern is consistent with the atrial organization signature expected from ablation of a single spiral wave with fibrillatory conduction to the rest of atria. CONCLUSION Temporally dense spatiotemporal assessment of atrial organization during the ablation of persistent AF is feasible and provides complementary information to cycle length measurements. Atrial organization starts locally and expands spatially in discrete jumps. The regularization of AF to atrial flutter exhibits characteristics of phase transition in complex systems.