Idiopathic ventricular arrhythmias originating from the right coronary sinus: Prevalence, electrocardiographic and electrophysiological characteristics, and catheter ablation

BACKGROUND: Ventricular arrhythmias (VAs) of the right coronary cusp (RCC) are not fully characterized. OBJECTIVES: To investigate the electrocardiographic and electrophysiological characteristics, mapping and ablation of RCC-VAs. METHODS: Among 256 consecutive patients undergoing electrophysiological evaluation and ablation of VAs of ventricular outflow tract origin, data were compared among 27 RCC-VAs, 50 VAs of the septal aspect of right ventricular outflow tract (RVOT), including from pulmonary artery, and 9 VAs of left coronary cusp (LCC). RESULTS: The only electrocardiographic characteristic that differentiated VAs originating from the RCC and RVOT was the amplitude of the R wave in lead I. During VAs of the RCC, the earliest activation site (EAS) in the right ventricle was localized in the middle-posterior septal region of the RVOT. The distance between the His bundle and the EAS in the RVOT in the RCC group was shorter than that in the RVOT and LCC group; the distance ≤ 29.4 mm, which rules out an RVOT and LCC origin, had 92.6% sensitivity and 100% specificity for RCC-origin speculation. Double or complex potentials were recorded in RVOT middle-posterior septal area surrounding the EAS in 20 of 27 RCC-VA patients (70%). Most of the successful ablation sites (24/27) were located in the anterior and upper margin of the RCC, close to the middle-posterior septal region of the RVOT. The prepotential (P1) amplitude and the P1-to-QRS complex interval may be indicators of successful RCC-VA ablation sites. CONCLUSIONS: RCC-VAs are not uncommon and have unique electrocardiographic and electrophysiological characteristics that distinguish an RCC origin of VA from RVOT and LCC origins. Most RCC-VAs were ablated successfully in the anterior and upper aspects of the RCC.