Background: Rotational excitation (rotor) is responsible for persistent AF (PeAF) maintenance. We hypothesized that PeAF creates the regions facilitating complex rotational activities (rotor substrates, RSs) but pulmonary vein isolation (PVI) can modify some RSs into more organized activation; RSs which cannot be modified by PVI may be targeted for PeAF ablation. ExTRa Mapping^TM, a custom-made mapping system (Nihon Kohden, Tokyo, Japan), creates phase maps (PMs) in a real-time manner by combining actual atrial electrograms and computerized virtual action potentials; it can automatically calculate the percentage of time in which rotors are observed within the recording area (non-passive activation ratio, %NP).
Objective: To examine the characteristics of RSs that are and are not modifiable by PVI.
Methods: In 40 PeAF patients, real-time phase mappings (ExTRa Mapping, Nihon Kohden) in the LA were performed with ExTRa Mapping system before/after PVI and calculated %NP. The area showing %NP>50% was defined as RS. When RS was observed in the same region before/after PVI, it was defined as unmodifiable RS. The spatial distribution of the RSs, average %NP of the RSs, and the time-ratio of visualized single PS/multiple PSs in the RSs were compared between the PVI-modifiable and PVI-unmodifiable RSs. After PVI, the PVI-unmodifiable RSs were additionally ablated; a one year AF free survival rate in PVI + additional RS ablation was compared to controls (PVI alone, n=52).
Results: Before PVI, RSs were globally distributed in the LA but more frequently observed in the anterior/bottom region. After PVI, most RSs were modified in the roof/posterior/septum region, but not modified in the anterior/bottom region. Unmodifiable RSs had higher %NP than modifiable RSs (64±8% vs. 60±8%, p<0.05). The time-ratio of visualized single PS/multiple PSs was unchanged between the two groups. A one-year AF-free survival rate was significantly higher in PVI+RS ablation (87%) than in PVI alone (73%, log-rank=4.882, p<0.05).
Conclusion: PVI can modify some RSs but RSs showing higher %NP in the anterior/bottom region remain to be modified. Additional PVI-unmodifiable RS ablation may improve the success rate in PeAF ablation.