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.