4.5 NPAs with a greater AWT
A previous study provided simultaneous endo-epicardial high-density
mapping data of breakthroughs during AF and demonstrated that the large
majority of breakthroughs are explainable by transmural
conduction.19 Recently, Parameswaran et al. analyzed
simultaneously acquired endo-epicardial right atrial recordings from 14
persistent AF patients undergoing cardiac surgery, collected with a
high-density grid electrode array (interelectrode distance of 3
mm).20 They demonstrated that endo-epicardial
dissociation is highly dynamic and wavefront propagation heterogeneous,
suggesting that targeting a single focus of the endo-epicardial
dissociation or breakthrough is unlikely to prevent recurrence of AF.
This is consistent with the concept of ExTRa Mapping, in which
persistent AF encountered in clinical practice is mostly driven by
spatially and temporally unstable rotors rather than stationary stable
rotors.5 To rapidly predict the atrial excitation
during AF, both a computer simulation (in silico) part and special
artificial intelligence part were incorporated into the ExTRa Mapping
system. The in silico part computed virtual atrial action potentials
based on an in silico model of the human persistent AF in combination
with the timing of the action potential generation determined by the
intra-atrial signals.21 Recent experiments have
successfully shown that the phase map sequence of ExTRa Mapping is
consistent with high-resolution optical mapping.6Ashihara et al. demonstrated a great catheter ablation outcome using
ExTRa Mapping in persistent AF patients for maintaining sinus
rhythm.5 This indicated that NPAs detected by ExTRa
Mapping should contain the true AF drivers. Therefore, we believed that
ExTRa Mapping would provide a more specific ablation target relevant to
the cause of AF.
It was previously reported that AF recurrence correlated with the
emergence of new AF drivers after catheter ablation, where they occurred
in locations distinctly different from those of the original
ones.22 To eliminate all of them, electrophysiological
mapping, such as ExTRa mapping, should be performed repeatedly, however,
it would result in a prolongation of the procedure time. Considering
this issue, LGE-MRI is useful for planning the ablation strategy, as it
can narrow down the target to be ablated preoperatively.