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.