Ablation procedure
Details of the AF ablation procedure performed at our institution have previously been described.13 Therefore, we present a brief description focusing on SVCI as follows. All CIEDs were interrogated prior to AF ablation, and bradycardia parameters were programed to VVI 30. In the defibrillator devices, tachyarrhythmia detection and therapy were switched off. All patients had undergone a wide circumferential PVI (CPVI) using a 3-dimensional mapping system (CARTO 3, Biosense Webster, Inc., Diamond Bar, CA) and a 3.5-mm open-irrigated tipped catheter (Navistar ThermoCool, ThermoCool SF, or ThermoCool STSF, Biosense Webster, Inc., Diamond Bar, CA). After the CPVI, an empirical SVCI was performed except in patients without electrical potentials 10 mm above the right atrium (RA)-SVC junction. Radiofrequency (RF) application was delivered below the circular mapping catheter placed 5–10 mm above the RA-SVC junction in a point-by-point fashion using a power of 25 W for <30 seconds or 30 W for <20 seconds. Before the RF application, high output pacing at 10 mA was performed on the anterolateral and posterolateral walls of the SVC. Ablation at the site, where phrenic nerve stimulation was observed, was avoided. If the RA-SVC conduction remained at the site of phrenic nerve stimulation, the RF was delivered carefully while the diaphragm movement on fluoroscopy was monitored using a power of 20 W, for up to 20 seconds. The endpoint of the SVCI was the elimination of SVC potentials recorded using the circular mapping catheter. The absence of dormant conduction with adenosine-triphosphate infusion was also confirmed. After AF ablation, all devices were tested again and reprogramed to baseline settings. A plain chest radiograph was taken to check the lead dislodgement on the day following AF ablation. All patients were followed up at the outpatient clinic at 1, 3, 6, 9, and 12 months after the ablation, then every 6 months thereafter. Recurrence was defined as documented atrial tachyarrhythmias (ATAs) on the electrocardiogram, 24-hour ambulatory monitoring, portable electrocardiographic monitoring, or data obtained from CIEDs (lasting >30 seconds). A second AF ablation session was attempted for recurrence of ATAs based on the physicians’ discretion.