Catheter Ablation -> Ventricular Arrhythmias -> Mapping & Imaging D-PO06 - Poster Session VI (ID 26) Poster

D-PO06-099 - Incremental Yield Of Programmed Stimulation From Within Abnormal Substrate: New Insights Into Site-specificity Of VT Induction (ID 1364)

 W. Wei: Nothing relevant to disclose.


Background: Induction of reentrant VT is occasional and is typically performed via programmed extrastimulus pacing in RV.
Objective: To examine the incremental yield of inducing VT from within the LV scar substrate.
Methods: We retrospectively studied all scar-related VT ablations in our center from Mar 2016 to Oct 2019. The majority of cases underwent noninvasive programmed stimulation(NIPS) from ICD leads before general anesthesia to identify a target VT and accepted invasive stimulation(IPS) from LAVAs within or adjacent to deceleration zones in LV. The stimulation and location to induce VT were analysed. Pacing sites were categorized as exit or isthmus sites (<25% or 25-75% TCL) based on the EGM-QRS and S-QRS during VT and pacing.
Results: 191 procedures for scar VTs were performed in 153 patients. 41 cases in which NIPS was not performed were excluded from analysis. 33%(49/150) cases were noninducible for sustained monomorphic VT via NIPS from the RV, where 65%(32/49) became inducible via IPS within LV scars. 38%(12/32) such cases were induced by burst, where 1/3(4/12) were induced by 1 beat pacing, other 62% were induced by programmed stimulation. 59%(19/32) cases were induced within the isthmus with paced morphologies close to VTs, including 12 induced at the exits, 3 at the isthmus sites and 4 at the entrances, while the rest 13 were induced in outer loops.
Conclusion: Programmed stimulation within abnormal substrate improve VT inducibility compared to RV stimulation. Stimulation at the exit of the circuit has higher yield than isthmus site to induce the matched morphology. Burst pacing is a site-specific method for VT induction that does not require extrastimuli for unidirectional block.