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

Due to their low prevalence in Europe, data on optimal treatment of ventricular arrhythmias (VAs) involving the left ventricular conduction system are scarce.

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.

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%.

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.