BACKGROUND: Ventricular arrhythmias (VAs) near the His-bundle comprise 9% of unexplained VAs and present challenges for ablation caused by the risk of atrioventricular block. OBJECTIVES: The authors studied the electrocardiographic (ECG) and electrophysiological characteristics of Para-Hisian (PH) VAs, comparing them with septal right ventricular outflow tract VAs. METHODS: From 210 patients with VAs between 2018 and 2024, 31 (14.7%) with PH-VAs and 23 (10.9%) with septal right ventricular outflow tract VAs were included. ECG characteristics of both were compared, and features differentiating left and right PH and supra- and infra-Hisian VAs were identified. RESULTS: Of 31 patients, 15 had VAs from the right PH site and 16 from the left. Median follow-up was 15 months (Q1-Q3: 14-21 months) for left infra-Hisian, 16 months (Q1-Q3: 14-20 months) for left supra-Hisian, and 14 months (Q1-Q3: 14-16 months) for right infra-Hisian and right supra-Hisian VAs (Q1-Q3: 14-15 months). PH-VAs had narrower QRS complexes (134 ± 19.6 ms vs 169 ± 24 ms
P <
0.05), R-wave in lead aVL (100% [31 of 31] vs 4.3% [1 of 23]
P <
0.001), and earlier R-wave transition at or before lead V CONCLUSIONS: PH-VAs exhibit unique ECG features based on their origins, and can be effectively treated without affecting atrioventricular conduction.