Identification of the SVC-RA junction and measurement of the SVC sleeve
After the complete PVI procedure, the voltage and activation maps of the SVC and RA were precisely reconstructed using the CARTO system with a 20-pole PentaRay®catheter (Biosense Webster, Diamond Bar, CA, USA) during sinus rhythm. The SVC-RA junction was defined as fused SVC potentials and RA potentials 12,13. The cut-off value of the voltage map was 0.5–0.1 mV. Less than 0.1 mV was defined as no electric potential (in the SVC, it was defined as no SVC sleeve). Then, the length from the SVC-RA junction to the top of the myocardial sleeve in the SVC was measured. The long and short diameters of the SVC at the height of the SVC-RA junction were also measured.