Comparison of patient and procedural characteristics
The CIED group comprised 34 patients (mean age, 57.9 ± 12.7 years; males, 64.7%), and 71 leads, including 44 pacing leads, 21 defibrillator leads, and 6 coronary vein leads, were assessed in this study. Details of patient and procedural characteristics are shown in Table 1. No significant differences in age, sex, AF type, and type of ablation catheters were found. Paroxysmal AF was the most dominant type of AF in both groups. The prevalence of structural heart diseases was significantly higher in the CIED group. The entire procedural time and the time needed to achieve SVCI were similar in both groups; however, the fluoroscopic time was significantly longer in the CIED group (15.8 ± 1.9 vs. 10.5 ± 1.8 min, P = 0.046). No phrenic nerve paralysis due to SVCI was observed in both groups. The success rate of the SVCI in the first session was 97.1% (33 of 34 patients) in the CIED group. A recurrence of ATAs was observed in 12 (35.3%) patients of the CIED group and in 10 (29.4%) patients of the non-CIED group, and all these patients had undergone a second session of AF ablation. The rates of SVCI reconnection and PVI reconnection in the second session did not significantly differ between the groups. In the second session for the CIED group, SVCI reconnection was observed in 9 of 12 patients (75.0%). The reconnection site corresponded with lead positions in all 9 patients. In 2 of 9 patients, SVCI could not be achieved in the second session. As a result, the successful rate of SVCI after the final ablation procedure was 91.2% in the CIED group and 100% in the non-CIED group, showing no statistically significant difference (P = 0.077). SVCI failed in 3 patients, and details of these 3 patients are described as follows. In the first AF ablation session, SVCI could not be achieved in only 1 patient. An atrial lead and a dual-coil defibrillator lead were implanted in this patient (Figure 1A). The ablation catheter used for this patient was a 3.5-mm open-irrigated tipped catheter without contact force-sensing technology (Navistar ThermoCool SF, Biosense Webster, Inc., Diamond Bar, CA). In the remaining 2 patients, electrical re-isolation of the SVC failed in the second session. One patient was implanted with 3 leads, including a 2.2-mm atrial pacing lead, 2.2-mm ventricular pacing lead, and an abandoned lead. A 3.5-mm open-irrigated tipped catheter with contact force sensing and surround flow technology (ThermoCool STSF, Biosense Webster, Inc., Diamond Bar, CA) was used for this patient. A 2.4-mm atrial lead and a 2.25-mm ventricular lead were implanted into the other patient. The ablation catheter used for this patient was a 3.5-mm open-irrigated tipped catheter without contact force-sensing technology (Navistar ThermoCool SF, Biosense Webster, Inc., Diamond Bar, CA).