Mapping and RFCA
Bipolar and unipolar intracardiac electrograms were filtered at 30–400
and 0.05–400 Hz, respectively, and the surface ECG was filtered at
0.05–30 Hz. If patients had sufficient VA with or without isoproterenol
(2–4 µg/min), local activation time mapping was performed to identify
the earliest bipolar ventricular electrograms, accompanied by a unipolar
QS pattern wave. On the other hand, if patients had an insufficient VA,
pace mapping was performed at a pacing cycle length of 500 ms. Then, the
paced and the spontaneous VAs were closely compared to determine the
target for RFCA. The site of VA origin was determined using the
electroanatomic maps from the RAO and LAO views.
Radiofrequency energy was delivered to the distal electrode of the
irrigated 3.5-mm tip catheter at a temperature limit of 55°C and power
setting of 30 W. In cases where the target was within the
great
cardiac vein near the anterior interventricular vein (GCV-AIV), the
power was started from 15 W and increased up to 30 W. In other cases
where the target was adjacent to the intense fibrous structures or there
was suppression and recurrence of VA, a power of up to 40 W was used.
The ablation duration of each site was approximately 60 s, with a
maximum duration of 120 s.
Successful ablation success was achieved when (1)
clinical
VA was eliminated at the end of the procedure; (2) clinical VA was
absent after 24 h of continuous ECG monitoring without antiarrhythmic
drugs; and (3) there was no recurrence of clinical VA during
>3 months of follow-up. All of these predescribed criteria
should be satisfied to achieve successful ablation.
Validation
study
After developing the algorithm for predicting OTVA origin, we validated
it by including another 100 patients from two different hospitals
between June 2020 and October 2022.