STUDY DESIGN A prospective study. OBJECTIVE A single center clinical trial on the analysis of intracardiac atrial electrogram waveform periodicity for catheter ablation of persistent atrial fibrillation with OCTARAY™ Mapping Catheter, as prospective randomized controlled study. HYPOTHESIS: The critical atrial substrates in maintaining persistent atrial fibrillation could be identified by non-linear electrogram morphology analysis in a point-by-point electroanatomic mapping. Based on the previous study, atrial substrate with high-similarity electrogram regions correlated with procedural AF termination and better long-term AF-free (1). Therefore, we proposed that the degree of waveform similarity plus the beat-to-beat sequential morphology (2) (duration of how many similar waveforms can maintain in sequence) would be even better to characterize the atrial substrate and could be potentially critical atrial substrate in prediction of sources of AF. As additional substrate mapping provided benefits compared to PVI alone in patients with persistent AF, we hypothesize that waveform periodicity adjuvant to electrogram similarity and phase mapping could be used to guide radiofrequency ablation in real time. The used of the OCTARAY™ Mapping Catheter could collected more AF electrogram and facilitate the mapping resolution and driver identification.