Clinical Impact of High-Intensity Targeted Ablation of Identifiable Critical Zones in Scar-Related Ventricular Tachycardia.

Background: Ventricular tachycardia (VT) isthmus boundaries correlate with a localized line of conduction block (LOB) identified by substrate mapping during baseline rhythm. In particular, a rotational activation pattern (RAP), which is characterized as a wavefront propagation pivoting around the edge of the fixed LOB accompanied by conduction slowing, may have a high proclivity toward re-entry.

Objectives: This study aimed to assess outcomes of ablation targeting the RAP around the LOB identifiable during substrate mapping.

Methods: We studied 81 patients (median age 68 years; 85% male; 25% ischemic cardiomyopathy) who underwent ablation primarily targeting the regions exhibiting a RAP around the LOB associated with clinical VT.

Results: High-resolution substrate mapping identified a RAP in 41 patients (51%). Of these, 30 patients (Group A) underwent ablation of an area with a radius >1 cm, including the targeted RAP regions. In 11 patients (Group B), RAPs were unable to be ablated because of the proximity of the RAP site to the conduction system, coronary arteries, or phrenic nerves, or based on the operator's discretion to avoid hemodynamic decompensation. The remaining 40 patients (Group C) had no identifiable RAP, and none of them had no mid-diastolic activities during VT due to intramural or contra-surface arrhythmogenic substrate. During 1-year follow-up, 83% freedom from VT recurrence was achieved in Group A, compared with 41% and 39% in Groups B and C, respectively (P = 0.003).

Conclusions: The identification of critical zones of the VT re-entrant circuit, which may be co-localized with regions hosting RAP around the LOB, as well as high-intensity ablation targeting these regions, appear to be important for successful ablation.