Long-term outcome of catheter ablation of left fascicular ventricular arrhythmias

BACKGROUND: Due to their low prevalence in Europe, data on optimal treatment of ventricular arrhythmias (VAs) involving the left ventricular conduction system are scarce. AIM: To report on clinical and procedural characteristics and long-term outcomes of European patients undergoing catheter ablation of primary ventricular complexes (PVCs) and ventricular tachycardias (VTs) involving the left ventricular conduction system. METHODS AND RESULTS: This study includes 27 retrospectively identified Caucasian patients (10/27 (37%) women, median age 44.5 (IQR 33-55.75) who underwent electrophysiological examinations at a tertiary ablation center over a period of 14 years (between 2009 and 2022). Mapping and ablation were performed via transaortic and/or transseptal approach. Post-ablation follow-up (FU) was performed via regular Holter-ECGs and clinical evaluations, or via structured FU within the prospective TRUST registry (ClinicalTrials.gov Identifier: NCT05521451). VAs were located in the left posterior fascicle (LPF) in 21/27 patients (78%), the left anterior fascicle (LAF) in 4 (15%), and the upper septum (US) in 2 (7%). Among patients presenting with arrhythmias involving the LPF, the majority (12/21, 57%) presented with sustained VTs, and 9/21 (43%) experienced PVCs/non-sustained (ns)-VTs. In contrast, among those with arrhythmias involving the LAF, the predominant clinical presentation was PVCs or ns-VTs (3/4, 75%). Of the two patients with arrhythmias involving the US region, one (50%) presented with PVCs and ns-VTs, and the other (50%) with sustained VT. Ablation was acutely successful in 24 patients (89%) with a procedure time of 130 ± 49 min. Three of the 27 patients (11%) underwent re-ablation due to early arrhythmia recurrence. No procedure-related complications occurred except left fascicular posterior block in four (15%) and a complete left bundle block in one patient (4%). Arrhythmia-free survival after a median follow-up of 30 (IQR 14-62) months was 73%. CONCLUSION: VAs predominantly presented as tachycardia involving the posterior fascicle and as PVCs involving the anterior fascicle and both can be treated by catheter ablation with favorable long-term clinical outcome.