Main findings
This is the first study to show the significance of the positional relationship between the EC site and right-sided anterior PVI line in successful PVI. We report the following findings: (1) In high-density LA mapping before ablation, an EC between the right-sided PV and RA was observed in 23/74 patients (31%); (2) In the on-the-line and outside-line groups, the success rate of first-pass isolation was high (91% and 100%, respectively), while it was low in the inside-line group (20%); and (3) Even in the presence of an EC, PVI could be successfully achieved without additional carina ablation by intentionally setting isolation lines.