A stepwise approach to the induction of idiopathic fascicular ventricular tachycardia

Noninducibility of the clinical tachycardia is a major limitation while mapping and ablating idiopathic fascicular ventricular tachycardia (FVT). There is very little data on systematic induction protocols in this entity. Our aim was to study the role of systematic induction protocols in patients with clinically documented ventricular tachycardia (VT).

Programmed electrical stimulation was performed at baseline from high right atrium, right ventricular apex, right ventricular outflow tract and from left ventricle as per the protocol. Programmed ventricular stimulation was performed at two drive cycle lengths up to three extrastimuli and short-long-short sequence. If FVT remained non inducible at baseline, pharmacological provocation with isoprenaline/atropine/phenylephrine was used based on the baseline atrio-ventricular Wenckebach cycle length.

This systematic induction protocol was studied in 68 patients with clinically documented FVT and sustained FVT was inducible in 64 patients (94 %). Of these 64 patients, pharmacological provocation was required in 18 patients (28 %) while in the remaining, sustained VT was induced at baseline. This high induction rate allowed ablation during tachycardia, which resulted in 100 % acute procedural success in the patients where sustained tachycardia could be induced. At a follow up of 29 ± 13 months, two patients (3 %) had recurrence.

Systematic induction protocol along with the appropriate use of pharmacological agents results in a high induction rate of FVT. This may result in more defined and limited ablation during tachycardia with better success rates and lesser recurrence.