Background The origin distribution of right-ventricular-outflow-tract
(RVOT) ventricular arrhythmias (VAs) remains unclear. There is limited
data on the ablation effectiveness of the reversed U-curve method
compared with the antegrade method. Objectives To investigate the origin
distribution of RVOT-type VAs and compare the ablation effectiveness of
the two methods. Method Consecutive patients who had idiopathic
RVOT-type VAs were prospectively enrolled. After activation mapping,
patients were randomly assigned to supravalvular strategy using the
reversed U-curve or subvalvular strategy using the antegrade method. The
primary outcome was initial ablation (IA) success, defining as the
successful ablation within the first three attempts. Results 61 patients
were enrolled from November 2018 to June 2020. Activation mapping
revealed 34/61 (55.7%) of the earliest ventricular activating (EVA)
sites were above the pulmonary valves (PVs). The IA success rate was
25/33(75.8%) in the patients assigned to supravalvular strategy as
compared with 16/28(57.1%) in those assigned to subvalvular strategy
(P=0.172). Logistic regression revealed a substantial and qualitative
interaction between the EVA sites and IA strategies
(Pinteraction<0.001). For multiple-comparison, either strategy
had a remarkably higher IA success rate in treating its ipsilateral EVA
sites than contralateral ones (P<0.0083). Conclusion Of the
idiopathic RVOT-type VA origins, half were located above the PV. The two
strategies did not differ in the primary outcomes. However, they
complement locating the EVA sites and facilitate ipsilateral ablation,
which produces a significantly higher IA success rate. (Chinese Clinical
Trial Registry number, ChiCTR2000029331)