High-density Approaches to Ventricular Tachycardia Substrate Ablation

Ventricular tachycardia (VT) ablation is a challenging procedure with significant clinical benefit for patients. The classic VT ablation approach centers on arrhythmia induction and entrainment of tachycardia to identify the critical components of a VT circuit. In the post-coronary reperfusion era, smaller infarct size and subsequently faster VT cycle lengths have led to an increased occurrence of unstable, unmappable VT cases, making the classic approach untenable. While approaches of signal-based substrate modification have shown clinical efficacy in the past, these approaches are sometimes imprecise and require extensive ablation. With the advancement of high-density (HD) mapping technology and recognition of functional tissue properties requisite for VT initiation and propagation, a more finely targeted VT ablation approach may be pursued. Benefits of HD mapping include better tissue and signal characterization, avoidance of ‘perpendicular blinding’ and better identification of VT putative channels. Functional characterization of tissue, such as isochronal late activation mapping or decremental evoked potential mapping, allow for the identification of functional slowing required for VT reentry. Pre-ablative imaging continues to play an increasing role in substrate characterization and pre-operative planning. Using a comprehensive, tailored, substrate-based functional HD VT ablation strategy can allow for safe and effective ablation of even unstable and unmappable VT.