Repolarization and Activation Mapping in Ventricular Tachycardia Ablation: the REDEMPTION Study

INTRODUCTION Among therapeutic strategies for ventricular tachycardia (VT), catheter ablation is indicated in reducing ICD shocks, improving quality of life and survival in selected cases, such as arrhythmic storm. However, clinical outcomes of VT ablation are hampered by not hemodynamically tolerated VTs in up to 30% of cases or not inducible/sustained VTs1. In this setting, substrate mapping during sinus rhythm is of utmost importance to guide ablation in the absence of a mapped reentry circuit.

Since slow conduction and unidirectional block are necessary for any reentrant arrhythmia, most of sinus rhythm approaches are based on slow and late wavefront conduction such as: late potentials (LPs), local abnormal ventricular activities (LAVAs) and isochronal late activation maps (ILAM). However, for reentry to occur, the returning wavefront needs to occur with a timing compatible with the recovery of the repolarization in the upfront tissue (wave tail). Based upon these premises, recently, novel strategies based on repolarization (or wave tail) have also been assessed.

Human VT reentry circuit is arguably the result of an interplay between both a delayed conduction and repolarization heterogeneities. Thus, a substrate mapping method evaluating slow conduction together with repolarization abnormalities may capture the complexity of the reentrant VT phenomenon.

METHODOLOGY INCLUSION AND EXCLUSION CRITERIA All consecutive patients undergoing VT ablation at Universitair Ziekenhuis Brussel (UZB), Brussels, Belgium will be prospectively enrolled if inclusion criteria will be fulfilled. Inclusion criteria will be: 1) VT ablation procedure; 2) High density endocardial or epicardial substrate EAM performed with the multipolar mapping catheter Advisor™ HD-Grid Mapping Catheter, (Abbott Labs, Abbott Park, IL, USA) in association with the EnsiteXTM Cardiac Mapping System, (Abbott Labs, Abbott Park, IL, USA); 3) Use of TactiFlexTM ablation catheter (Abbott Labs, Abbott Park, IL, USA).

Exclusion criteria will be: 1) use of a different EAM mapping system. Clinical VT will be defined as a VT that occurs spontaneously based on analysis of 12-lead ECG QRS morphology, following current guidelines. Sustained VT will be defined as lasting more than 30 s. All patients will sign an informed consent. All data will be collected and updated in a centralized online database. The study will comply with the Declaration of Helsinki; the ethic committee will approve the study.