Fast and the Furious: Electrogram Drift: Dynamic Analysis of Acquired Electrograms to Optimize Discrimination of Ventricular Tachycardia Substrate.

Abstract

See Article by Kuroki et al > “It don’t matter if you win by an inch or a mile. Winning’s winning.” > > —Dom Toretto | The Fast and The Furious (2001) The foundation for ablation of ventricular tachycardia (VT) in patients with structural heart disease lies in (1) identifying relevant substrate, (2) proving that said substrate contributes to arrhythmogenesis, and (3) ablating that substrate. Many investigators, however, espouse pure substrate-guided approaches that may supplant step 2, wherein targeting of perceived substrate, as defined by voltage cut offs or signal characteristics, is performed in lieu of proving the relevance of that site or region to arrhythmogenesis. In fact, pure substrate-guided approaches to ablation, particularly in infarct-related VT, have been shown to have a reasonable likelihood of success in both retrospective studies and clinical trials.1–4 However, the best method for defining substrate, either before or during invasive electrophysiological procedures, remains an area of active study. The publication in this issue of Circulation: Arrhythmia and Electrophysiology by Kuroki et al5 present yet another approach to using acquired electrogram signals to optimize identification of critical targets for ablation. Understanding the relevance of their findings needs to be considered in the context of work to date on defining substrate for ventricular arrhythmogenesis and the associated pitfalls of existing approaches. In structural heart disease, it is the existence of electrically active circuits with conductive properties sufficiently different from that of surrounding normal myocardium that drives VT. Generally, but not always, these potential circuits exist in regions of the otherwise dense scar as complex connections between variably healthy regions of the myocardium. Thus, in the structurally diseased heart, these circuits may present themselves to the electrophysiologist as fractionated signals, late potentials (reflecting slow or complex wavefront propagation) or low-voltage regions. However, the presence of such …