Special electrophysiological characteristics of pediatric idiopathic ventricular tachycardia

Idiopathic ventricular tachycardia (VT) is an important pediatric arrhythmia but relevant studies in Asian cohort are rare. We determined the electrophysiological characteristics and outcomes of this rhythm disturbance.From an institutional database, patients aged <18years without structural heart disease who have sustained monomorphic VT (longer than 30s) during 1995-2016 were enrolled.We enrolled 57 idiopathic VT patients (male:female=31:26). The initial presentation included palpitation (64.9%) and shock (12.3%). The electrocardiography revealed relatively short QRS duration (123±18ms) and absence of ventriculoatrial dissociation in 33.3% of the patients, causing initial misdiagnosis in 29.8% of these patients. Patients with a VT onset age of <10years were more likely to have a left bundle branch block morphology (52.2% vs. 11.8%, p=0.001) and spontaneous recovery than those with a VT onset age of ≥10years. An electrophysiology study in 44 patients revealed that the most common arrhythmia focus was the left ventricular septal area (78%), called fascicular VT. Radiofrequency ablation showed a satisfactory success rate (90%) and fair recurrence rate (14.3%). Tachycardia-induced cardiomyopathy was noted in 14% of the VT patients and cardiac function returned to normal in 1-18months (median, 3months) after successful ablation.In an Asian pediatric population, VT has distinct electrophysiological characteristics including dominant left ventricular origin, narrower QRS duration, and more symptomatic presentation. Transcatheter ablation is effective against VT, and the associated cardiomyopathy often resolves rapidly after successful ablation.