The sites overlapping with LVAs
In the previous study, 77% of the high-DF sites overlapped with LVAs in the LA13 using conventional mapping catheters, while only 2.6% (22 sites out of 835) overlapped using the HDG in this study. However, there was a significant difference in the number of high-DF sites overlapping with LVAs between the patients with and without recurrent AF/AT. The HDG might drastically exclude false LVAs, which would help detect the AF substrate more accurately.
Furthermore, though the number of %NP≧50% sites overlapping with LVAs in the LA was greater, there was no significant difference in that number between the patients with and without recurrent AF/AT. The %NP indicated the frequency of the presence of rotors within a relatively large mapping area (diameter of 2.5 cm), and the area overlapping with LVAs may not always reflect the exact overlapping sites between the rotors and LVAs.
High-DF areas change spatiotemporally and the DF based ablation is still controversial.12 However, drivers are harbored within/in the vicinity of LVAs, and fractionated activity, rotational activity, and discrete rapid local activity during AF in LVAs may contribute to the formation of high-DFs.7,15 The selection of high-DF sites overlapping with LVAs as targets may correct the shortcoming of an ablation based on the DF.13 In this study, a combination of frequency mapping and LVA mapping using the HDG could detect the critical selective atrial substrate necessary to maintain AF. Therefore, this strategy using the HDG could avoid any excessive RF applications as compared to that using conventional mapping.