Electrocardiographic Characteristics of Ventricular Arrhythmias Originating From High Right Ventricular Outflow Tract and Pulmonary Artery

Background: Ventricular arrhythmias (VAs) may originate from the right ventricular outflow tract (RVOT) below the pulmonary sinus cusps (PSCs) or from the pulmonary artery (PA) above the PSCs. However, the electrocardiographic (ECG) characteristics of these VAs are not well defined. Objective: This study aimed to investigate the ECG characteristics of VAs originating from the high RVOT and PA. Methods: Patients who underwent catheter ablation for VAs originating from the RVOT or PA were retrospectively reviewed. Patients with VAs exhibiting a left bundle branch block pattern and an inferior axis on ECG, who also underwent pulmonary artery angiography, were included. Three-dimensional electroanatomic mapping was performed for all patients. The origin of the VAs, either below the pulmonary sinus cusps (Group 1: high RVOT group) or above the pulmonary sinus cusps (Group 2: PA group), was confirmed via PA angiography. Results: Thirty-seven patients were in Group 1, and 36 were in Group 2. In Group 2, significantly shorter R wave peak times (RWPT) were measured in leads II, III, and aVF on surface ECG during VAs. The cutoff values for RWPT were 66, 66, and 69 ms, respectively, with high area under the curve values of 0.944, 0.944, and 0.913, respectively. Conclusion: VAs originating from the PA exhibit shorter RWPT in leads II, III, and aVF on surface ECG, distinguishing them from VAs originating from the high RVOT. These findings can aid in preprocedural planning, facilitating the mapping and ablation of the supra-PSC region based on surface ECG characteristics.