Limitations
This study had some potential limitations. First, it was a retrospective
and observational study at a single institute. We did not have many
patients with persistent AF, which might have caused a statistical bias.
Second, we did not perform a substrate ablation such as a line, complex
fractionated atrial electrogram (CFAE), rotor, and LVZ ablation.
However, recent studies have revealed that only the efficacy of the PVI
has been proven.25-28 In this study, there was no
significant difference in the non-PV foci between the two groups. Third,
we also considered the effects of the confounding predictors for AF
recurrence. However, the IDF threshold was a useful predictor for AF
recurrence because the IDF remained after a multivariate analysis after
adjusting for the patient factors.