The Location of the Potential FCB Region
Critical areas of arrhythmogenesis often occur in diseased tissue with
low-voltage areas that indicate
the scarring zone. The potential in scar areas could be recorded as
ESAs, LDPs or FPs, each of which acts instead of a different mechanism
on arrhythmias.8-11 One AT that converted to another
kind of AT during ablation could occur due to various causes (abnormal
automaticity, triggered activity or reentry). The FCB region we
described in this study was more common with scar-related reentry and
often could be found near the scarring zone. While the potential of
these regions could convert between DPs, FPs and normal potential
formation in the different ATs, it was still low voltage compared with
that of normal tissue in some ATs or sinus rhythms. This
electrophysiological feature in large part may be due to scarring of the
atrium due to various heart diseases, while normal tissue could not be
seen. Second, except for the effect of the scarring, the regions where
FCBs occurred were observed more commonly in the junction between the
left atrial appendage and anterior wall of the left atrium (in 3) and
the junction between the roof and atrium of the left superior PV (in 2),
where Bachmann’s bundle is located.12 These positions
are associated with fiber crisscrosses that may exhibit more electric
anisotropy. The scarring may affect the homogeneity of conduction in one
orientation during ATs. In patients with previous AF ablation, the first
MAT may be due to the circumferential pulmonary vein isolation (CPVI),
and the FCB would be related to damage to the previous ablation line.