Long-term outcome of catheter ablation of idiopathic ventricular arrhythmia originating from right ventricular outflow tract guided by a Lasso catheter

Purpose: Radiofrequency Catheter Ablation (RFCA) has became primary therapy for idiopathic Ventricular Arrhythmias (VAs) originating from Right Ventricular Outflow Tract (RVOT). This study was to investigate the clinical outcome of catheter ablation of VAs originating from RVOT guided by a multielectrode circular mapping catheter (Lasso catheter). Methods: Among 358 consecutive patients who underwent ablation for idiopathic VAs, 199 patients (55.6%) were found to have an ablation site at RVOT area. RFCA using Lasso catheter (25 mm size adjustable or 30 mm fixed diameter) was performed in 138 patients (69.3%, 43±13 years, M/F: 52/86). The remaining 61 patients (31.7%) were performed with 3 dimensional noncontact mapping system (ESI). We divided Lasso-guided ablation as two groups according to clinical outcome during follow-up: successful group vs. unsuccessful group. Results: In 138 patients with Lasso-guided ablation, 97 PVCs, 28 non-sustained VT and 13 sustained VT were identified as presenting arrhythmia. In 22 patients (15.9%), a Lasso catheter was not beneficial to identify adequate ablation site because of large RVOT dimension (n=14) or inadequate position of Lasso catheter (n=8). The ablation was failed in 1 patient and 34 patients had recurrent VAs after ablation. VAs recurrence was not different between Lasso-guided ablation and ESI-guided ablation (34/138, 24.6% vs. 18/61, 34.5%, P=0.47). However, shorter fluoroscopic and procedure time were observed in Lasso-guided ablation (20.7±13.2 minutes vs. 28.9±13.3 minutes, P<0.001, 82.7±32.9 minutes vs. 144.6±63.9 minutes, P<0.001, respectively). In 8 of 34 patients with VAs recurrence, redo ablation procedure was also performed guided by a Lasso catheter. A fragmented potential during VAs at ablation site was seen in 12.5% (13/104) of successful group, but none in unsuccessful group (P=0.03). No patients had procedure-related complications. Conclusions: The Lasso catheter is useful for determining the optimal ablation site in most patients with idiopathic RVOT VAs. VAs recurrence after Lasso-guided ablation was not different from ESI guided ablation. The shorter fluoroscopic and procedure time was benefit of Lasso-guided ablation. The presence of fragmented potential at successful ablation site was related to better clinical outcome.