Real-Time Phase Mapping
In the same areas where the DF mapping was performed, mapping during AF was simultaneously performed using an online real-time phase mapping system (ExTRa MappingTM, Nihon Kohden Co., Tokyo, Japan) as described previously.16 This mapping system was based on 41 bipolar intraatrial electrograms (including 9 virtual electrograms) recorded by a deflectable 20-pole spiral-shaped catheter with a diameter of 2.5 cm. The contact was confirmed by the recorded electrograms, fluoroscopy, and 3D geometry. The distance between a mapping point and the geometry surface created by the EnSite NavX was set at 5 mm. The data sampling was adopted as good contact in areas where sufficient electrograms could be recorded from the vast majority of the electrodes. Based on the 5-s wave dynamics during AF, each phase map was automatically created by ExTRa Mapping. Non-passively activated areas, in which rotational activations were frequently observed, were automatically detected by ExTRa Mapping. The value of the “non-passively activated ratio” (%NP), which is the ratio of the form of rotors and multiple wavelets assumed to contain AF drivers to the recording time, was automatically calculated from the 5-s real-time phase map created by ExTRa Mapping.16 Of the 5-s map, the activation sequences during 720 ms (60 ms×12 consecutive time windows) of representative episodes were depicted as images.