Background

Idiopathic Fascicular Ventricular Tachycardia (IFVT) accounts for less than 10% of all VTs and represents the most common idiopathic ventricular tachycardia of the left ventricle. 

This study reports on clinical and procedural characteristics and the long-term outcome of patients undergoing catheter ablation of premature ventricular complexes (PVC) and ventricular tachycardias (VTs) arising in proximity of the left ventricular conduction system. 

Methods and results

This study includes 27 patients (17 male, 45 ± 17 years; 10 females, 50 ± 11 years) who underwent electrophysiological examinations at a tertiary ablation center over a period of 14 years (2009 to 2022). Follow-up was performed via regular Holter-ECGs and clinical evaluations, or via structured follow-up within the prospective TRUST registry.

In 21/27 patients (77.8%), the left posterior fascicle (LPF) was involved in the IFVT. In 4 (14.8%) the left anterior fascicle (LAF) was involved and in 2 (7.4%) patients an origin in the upper septal (US) area was demonstrated. 22/27 (81.5%) patients had a preserved left ventricular ejection fraction (LVEF) and only 5 (18.5%) patients had a LVEF less than 50% at the time of presentation.

14/27 (51.9%) patients presented with PVC or non-sustained VTs with the following distribution: 10 (71.4%) originating from the LPF, 3 (21.4%) from the LAF and 1 (7.1%) from the US. 21/27 (77.8%) patients presented with sustained VTs: 16 (76.2%) arising from the LPF, 4 (19%) from the LAF and 1 (4.8%) from the US. However, only 2 (7.4%) patients presented in sustained VT at the beginning of the EP procedure. In 16 (59.3%) patients a sustained VT was induced during the EP study via isoprenaline and/or programmed ventricular stimulation. Mean QRS duration of the VT was 124.5 ± 14.6 msec.  In 21 (77.7%) patients only a retrograde approach was used, in 3 (11.1%) patients a retrograde and an additional transeptal approach and in only 3 (11.1%) patients solely a transeptal approach. Mean number of radiofrequency applications was 11.8 ± 12.6 (30 to 40 Watts, 27545.6 ± 30524.4 Joules).

FVT ablation was acutely successful in 24 patients (88.9%). In 2 patients (7.4%) no ablation was performed due to inability to induce VT under sedation. 3/27 patients (11.1%) underwent re-ablation due to FVT recurrence after previous ablation procedures. Moreover, 3 (11.1%) additional patients underwent repeated VT ablations during follow-up, but the arrhythmia originated from a different LV area. No procedure-related complication occurred. In 4 patients (14.8%) left fascicular posterior block was caused by ablation and in 3 (11.1%) patients a complete left bundle block. Mean procedure time was 130 ± 48.9 minutes.

Conclusion

Ablation of FVT in a tertiary ablation center is associated with a high single procedural success rate of 88.9% during long-term follow-up, with a mild risk of fascicular injury. 11.1% of patients underwent re-ablation due to FVT recurrence.