Protocol of rapid electrical stimuli from the SVC
Rapid electrical stimuli were delivered at a portion of the shortest SVC-ERP to induce AF. Pacing with a 2-ms duration and three times the voltage of the threshold was delivered as 40 beats of pacing with an initial pacing cycle length (PCL) of 500 ms, which was shortened by 50-ms increments down to 250 ms, after which the PCL was shortened by 10-ms increments from 250 ms to 160 ms 13. In the case of a Wenckebach conduction block or two-to-one SVC-RA conduction block as the PCL was shortened without AF induction, these groups were assigned to the non-SVC-induced group (non-SIG). If AF was induced (Figure 2), these groups were assigned to the SVC-induced group (SIG). SVC isolation was performed only in patients with reproducible induction of AF from the SVC using adenosine triphosphate or isoproterenol, and there was a sufficient margin of at least 1 cm from the sinus node to the isolation line.