Introduction
Ventricular arrhythmias (VAs) are one of the most common arrhythmias encountered in clinical practice. VAs with left bundle branch block and inferior axis morphology frequently originate from right ventricular outflow tract (RVOT).1 Mapping and ablation of RVOT-type VAs by antegrade manipulating catheter in the RVOT has been well established.2 It had the highest acute procedural success (93%) and long-term success rate (82%) comparing to other VA origins.3 The general concept was that the VA origins are mainly beneath the pulmonary valve (PV).4 However, myocardial extensions above the PV are common.5 VAs originating from the pulmonary sinus cusps (PSCs) are receiving increasing attention.6 They could be underestimated by the interposed PVs, which would blur electric signals and hinder catheter contact.7 A recent study introduced a reversed U-curve method which ablated 90% RVOT-type VAs in the PSCs.8 The reversed U-curve method trended a higher immediate and long-term success compared with the antegrade method.8–10 A proof of VA origin is where successful ablation is performed and where ablation results in a better outcome. The general concept of subvalvular origins in RVOT-type VAs was questioned. The data on directly comparing the ablation effectiveness between the antegrade and reversed U-curve method were limited.
We hypothesized that many origins of idiopathic RVOT-type VAs are above the PV. The ablation effectiveness by reversed U curve and antegrade method are different according to the origins. In this prospective single-center open-label randomized controlled trial, we aimed to investigate the distribution of earliest ventricular activation (EVA) sites in patients with idiopathic RVOT-type VAs and compare the initial ablation success rate of the reversed U-curve method and the antegrade method.