Ablation-Induced Change in the Course of Fascicular Tachycardia - IDSS 2016 - The 13th International Dead Sea Symposium, March 6-9, 2016, David Intercontinental Convention Center, Tel Aviv The 13th International Dead Sea Symposium (IDSS) on Innovations in Cardiac Arrhythmias and Device Therapy

Avishag Laish-Farkash ¹ Avi Sabbag ² Yoav Michowitz ³ Michael Glikson ² Aharon Glick ³ Amos Katz ¹ Vladimir Khalameizer ¹

¹Electrophysiology Unit, Cardiology Department, Barzilai Medical Center, and the Faculty of Health Sciences, Ben-Gurion University of the Negev
²Davidai Arrhythmia Center, Leviev Heart Center, Sheba Medical Center and Tel Aviv University
³The Department of Cardiology, Tel Aviv Sourasky Medical Center, and Tel Aviv University

Aim: Multiform fascicular tachycardia (FT) was recently described as a ventricular tachycardia (VT) that has a reentrant mechanism using multiple fascicular branches and produces alternate fascicular VT forms. Ablating the respective fascicle may cause a change in the reentrant circuit resulting in a change in morphology, and ablation of the septal fascicle is crucial for successful ablation.

We describe four cases of FT in which ablation induced a change in QRS morphologies and aggravated clinical course.

Methods and Results: Four out of 57 consecutive FT cases in three institutions were retrospectively analyzed and found to involve multiform FT. They underwent electrophysiological study, fascicular potential mapping, and electroanatomical mapping. All patients initially had FT with right bundle branch block (RBBB) and superior axis morphology. Radiofrequency catheter ablation (RFCA) targeting the distal left posterior fascicle (LPF) resulted in a second VT with an RBBB-inferior axis morphology that sometimes became faster and/or incessant and/or verapamil-refractory in characteristics. RFCA in the upper septum abolished the second VT with no complications and uneventful long-term follow-up.

Conclusion: The change in FT morphology during ablation may be associated with a change in clinical course when shifting from one route to another and may aggravate symptoms. Targeting of the proximal conduction system (such as bifurcation, LPF, left anterior fascicle, high septal/auxiliary pathway) may serve to solve this problem.