RF Ablation
The ablation strategy was adopted depending on the activation mapping
result. Localized reentry aimed to find the isthmus region, which was
always located between 2 anatomic barriers, consisting of either the
natural MA or pulmonary vein (PV) or acquired ESAs or late diastolic
potentials (LDPs) and showed fragmented potentials. All the ATs of
localized reentry converted to another AT after fragmented potential
ablation. Remapping of the new tachycardia showed that an isthmus, which
had been a bystander in the previous tachycardia, had become a critical
part in the new circuit in 2 patients (Fig. 1C). The AMATs ablated the
narrowest bridge of conducting tissue between scars or anatomical
obstacles. The 4 perimitral flutter circuits were ablated by a line
connecting the MA to the left superior PV (n=3) and the right superior
PV (n=1). The peri-roof circuits were ablated by joining the PV to the
contralateral superior PV across the LA roof (n=2). CTI was ablated in 2
patients due to the CTI-dependent AT in the first mapping. The FCB areas
were never the target ablation site after mapping the mechanism of the
ATs, but some of the suited ablation sites could be near the barrier
formed by them (Fig. 2). No patients received further substrate-modified
ablation in AT or sinus rhythm.