Study design
The present study is a prospective single-center open-label randomized controlled trial. The study design was illustrated in Figure 1. After activation mapping of RVOT, PSCs and pulmonary artery (PA), the patients were randomly assigned to initial ablation (IA) with the supravalvular strategy using the reversed U-curve method and the subvalvular strategy using the antegrade method. Randomization was performed by tossing a coin. Ablation attempts were performed with uniformed power of 30w, duration of 10s, and irrigation rate of 17ml/min. Effective ablation was defined as suppression of VA by the ablation attempts. Isoproterenol was administrated to increase the frequency of premature ventricular contraction if necessary. Once effective ablation was identified, ablation was continued for 60s~90s. Each ablation application, including ablation attempts, was counted. Successful ablation was defined as non-inducibility of the clinical VAs with isoproterenol elicitation for 30 min. IA success was defined as the successful ablation within the first three ablation applications by the assigned strategy. IA failure included the following situations. Firstly, successful ablation was not achieved with more than three ablation attempts by the assigned strategy. Secondly, the IA targets and EVA sites were contralateral to the PVs, and the distance from EVA site to PVVJ was more than 10mm. Thirdly, the operator had the discretion to declare IA failure after at least one ablation application for the patients whose targets and EVA sites were contralateral to the PVs. Patients with IA failure were managed with the other ablation strategy.