Introduction: Modulation of atrial fibrillation (AF) drivers has been proposed as one of the effective ablation strategies for non-paroxysmal AF (Non-PAF). The efficacy of AF modulation is usually confirmed by increase in AF cycle length (AFCL) during ablation. However, confirming such efficacy is difficult because clinically available phase mapping systems visualizing AF wave dynamics are restricted for offline use and the spatial resolutions of the systems are not so high (1-3 signals/cm2). Moreover, it is unclear whether the AFCL increase really reflects AF driver modulation.
Hypothesis: Because AFCL measurement sites are not always located in the vicinity of the AF drivers, the degree of Non-PAF driver modulation is refrected by the organization of visualized AF wave dynamics rather than the AFCL increase.
Methods: To visualize the AF driver, we recently developed the higher spatial resolution (~8 signals/cm2) online realtime phase mapping system (ExTRa MappingTM) based on 41 bipolars signals recorded by a spiral-shaped catheter. Then we applied the system to consecutive 22 patients with Non-PAF, which was easily induced even after pulmonary vein isolation. Just before and after the AF driver modulation achieved by the ablation targeting highest top 5 %NP areas, we calculated (1) AFCL based on intraatrial signals and (2) %NP (the ratio of non-passively activated rotor period-to-recording time) reflecting AF organization level based on the ExTRa Mapping system (see Figure, top).
Results: (1) Non-PAF free ratio after 11±4 months follow-up was 72% in 18 patients out of the 3 months blanking period. (2) The outcome of the Non-PAF ablation had no significant relationship with the AFCL change but with the %NP decrease (Figure, bottom).
Conclusion: Modulation of Non-PAF drivers should be evalulated by re-mapping of the Non-PAF wave dynamics by employing online realtime phase mapping system rather than just confirming the AFCL prolongation during Non-PAF ablation.