Limitations
First, because this was a retrospective observational study with a
relatively small number of patients, biases common to non-randomized
studies could not be eliminated. Second, we excluded patients who could
not return or maintain sinus rhythm before PVI. Therefore, the
prevalence of an EC in the total AF ablation cohort remains unknown. In
addition, we confirmed the presence of an EC during RA pacing by Ripple
mapping and Coherent mapping. If we had changed the pacing site in each
case, we might have detected more or lesser ECs. In the EC-negative
group, eight patients required additional carina ablation. In these
cases, an EC might have been overlooked. This may partly explain the low
success rate of first-pass isolation in the EC-negative group. Third,
the duration of follow-up was relatively short, and there were only two
cases in which the second procedure was performed. We could not evaluate
long-term outcomes and PVI durability in this study.