Investigating Origins of Ventricular Arrhythmia Arising From Right Ventricular Outflow Tract and Comparing Initial Ablation Strategies

Background: The origin distribution in right ventricular outflow tract (RVOT) ventricular arrhythmias (VAs), as well as the initial ablation effectiveness of reversed U-curve method and antegrade method, remains unclear. Objectives: To investigate the origin distribution of RVOT-type VAs and compare the initial 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, defined as the successful ablation within the first three attempts. Results: Sixty-one patients were enrolled from November 2018 to June 2020. Activation mapping revealed that 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). Multivariate analysis revealed a substantial and qualitative interaction between the EVA sites and IA strategies (p(interaction) < 0.001). 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 supravalvular and subvalvular strategies did not differ in IA success rates. However, they were complementary to reveal the EVA sites and facilitate ipsilateral ablation, which produces a significantly higher IA success rate. Clinical Trial Registration: Chinese Clinical Trial Registry number, https://www.chictr.org.cn/showproj.aspx?proj=45623, ChiCTR2000029331.