Distribution of AF substrate
To date, atrial fibrosis, LVA, CFAE, AF rotor were considered as AF
substrates.3,11-14The left atrial fibrosis was visualized by the LGE-MRI and the LGE site
was heterogeneously distributed in AF patients. Higuchi et al. reported
that the LGE site was highly distributed in the left PV antrum near the
posterior wall side and spread on the posterior and anterior wall with
AF progression.15 The
LGE was more widely distributed in patients with persistent AF compared
with patients with paroxysmal AF, especially on the posterior and
anterior wall. Notably, the LGE site was likely distributed around LAA
on the anterior wall in the progressed AF patients. Our study also
demonstrated that the patchy LGE site was predominantly distributed at
PV antrum and LAA base, which was completely consistent with their
results.
The LVA was reported to be mainly found in LA septum, anterior LA and LA
posterior.16 Of
interest, Chen et al. reported that LGE sites were present at 61% of
LVAs, whereas LVAs were present at 28% of LGE
sites.17 Those findings
indicated that the distribution of the LGE sites could not completely
overlapped with that of the LVAs. The LVA distribution could depend on
the mapping resolution, pacing site, cardiac rhythm or use of the
cardioversion. Furthermore, the patchy LGE site was sometimes
underestimated which depended on the visualization method. This might be
the reason why the distribution of the LVA were not completely
concordant with that of the LGE.
The distribution of CFAE were most commonly located in the LA posterior
and PV antral region.18The distribution of spatiotemporal electrogram dispersion area were
equally distributed at PV, LAA, LA posterior, LA anterior and LA roof.
The distribution was unlikely similar to that of the patchy LGE site.
The relationship between CFAE, spatiotemporal electrogram dispersion
area, LVA and atrial fibrosis were complex and it was still in debate.
AF driver detected by a 252-electrode vest for body surface mapping were
predominantly located in the PV antrum and LA bottom, subsequently
around the LAA.19 Their
results were likely consistent with our results. Cochet et al. concluded
that the number of AF driver related to the extent of LGE, with the
location of AF driver clustering to LGE sites.20 This strongly
indicated that the LGE site could be one of the possible AF substrates
and it was considered as an ablation target, which strongly supported
our ablation strategy.