3.3. Procedural Outcomes
The number of VT morphologies documented prior to ablation, which were
considered clinical VTs, was 1 (IQR, 1 – 1; range, 1 – 5; total 83)
(Table 1), and the number of VT morphologies documented during the
procedure was 2 (IQR, 1 – 2; range, 0 – 10; total 126) (clinical VT
was 1 [IQR, 1 – 1; range, 0 – 5; total 66], and non-clinical VT
was 1 [IQR, 0 – 1; range, 0 – 9; total 60].) (Table 2).
Among the 83 clinical VTs, 19 (23%) persisted incessantly at the
beginning of the ablation, 47 (57%) were induced during the procedure,
and 17 (20%) were not induced during the procedure (Supplementary Table
1.). Among the 66 clinical VTs, which were documented during the
procedure, an adequate activation map could be acquired in 24 VTs
(36%). The critical isthmus could be identified in 35 clinical VTs
(53%); for 26 VTs non-inducibility after ablation could be achieved,
and 9 VTs could not be eliminated because the isthmus was deep (7 VTs)
or a coronary artery was nearby (2 VTs).
Table 3 shows the ablation data per patient. All clinical VT isthmuses
were identified and ablated, and those VTs could not be induced
thereafter in 18 patients (28%, Group A); 12 patients (19%) were found
by the presence of MDPs and VT termination during the RF ablation, and 6
patients (9%) were found by MESs. On the other hand, all or some
clinical VT isthmuses could not be identified or were identified and
ablated but remained inducibility in 46 patients (72%, Group B). Among
them, 8 patients (13%) underwent ablation after identifying the
clinical VT isthmus, but the ablation failed because the isthmus was
deep (6 patients) or a coronary artery was nearby (2 patients). In 4
patients (6%), some but not all clinical VT isthmuses were ablated, and
in 2 patients (3%) only a nonclinical VT isthmus ablation was
performed. Further, thirty patients (47%) underwent only a substrate
ablation because no VT isthmuses could be identified.