Supravalvular catheter ablation of idiopathic ventricular tachycardia arising from the mitral annulus: a case report.

Background: Although idiopathic ventricular arrhythmias most commonly originate from the outflow tracts, they may also arise from the mitral annulus and the left ventricular (LV) summit. While acute ablation outcomes have improved, catheter ablation of arrhythmias arising from these regions remains particularly challenging due to their complex anatomy. Case summary: A 19-year-old male athlete experienced sustained palpitations during exercise, followed by syncope. An implantable loop recorder documented wide QRS complex tachycardia during exercise. An electrophysiological study induced ventricular tachycardia (VT) arising from the mitral annulus, with the earliest activation recorded at an epicardial site in the distal cardiac vein. At first, endocardial ablation from the LV was performed; however, its therapeutic efficacy was limited. We tried ablation via a supravalvular approach from the left atrium (LA). The LA site was anatomically closer to the epicardial earliest activation site (epi-EAS) than the LV site (5.8 mm vs. 13.9 mm). Local electrograms at the LA site preceded the QRS onset by 34 ms, whereas those at the LV site preceded the QRS onset by 13 ms. Radiofrequency energy delivered from the LA successfully terminated the VT within 12 s and rendered it non-inducible. Discussion: This case demonstrates that a supravalvular LA approach can effectively suppress VT originating from the mitral annulus when conventional LV endocardial ablation is insufficient. Earlier activation timing and closer anatomical proximity to the epicardial earliest activation site supported the superiority of the LA vestibule as an ablation target. This strategy may serve as a valuable alternative in anatomically challenging cases.