Abstract 1783: Insights into Delayed Potential Detection by High Resolution Scar Mapping of Life Threatening Ventricular Arrhythmias in Patients with Ischemic Cardiomyopathy
Background Sinus rhythm (SR) substrate mapping is beneficial to find possible underlying reentrant circuits in life threatening ventricular tachyarrhythmias (VTs) after myocardial infarction, but the overall success rate of radiofrequency ablation guided by conventional substrate mapping is still low. We thus invented a new high-resolution (HR) substrate mapping technique to more precisely clarify the underlying substrate that might be the VT reentry circuit. However, recent reports suggested a delayed potential (DP) guided ablation is effective to treat reentrant VT. We hypothesized that ablation lines designed by HR substrate map can eliminate all potential isthmuses and can eliminate most DPs within the VT circuit. The aim of the study was to quantify whether elimination of DPs could be performed by linear ablation based on HR substrate map.
Methods There were 20 patients (pts) with VTs and ischemic cardiomyopathy who underwent HR substrate mapping during SR and linear ablation to eliminate all possible VT isthmuses. Ablation lines were made either between a scar-scar and/or anatomical obstacle-scar.
Results The mean number of sites mapped was 284±58 points/pt. A scar area was defined as a local electrogram amplitude of <0.1mV and non-capture with local bipolar simulation. A normal amplitude was defined as that >0.6mV. A mean of 1.9 isthmuses were identified in 16 pts within low voltage zone sites around the scar area, and all isthmuses were linearly ablated. The remaining 4 pts had no scar/low voltage areas on the endocardial mapping. With this linear ablation design, 19.5±13.6 DPs were located within low voltage areas and most DPs (86%) detected could be ablated during linear ablation between the isthmuses. After completion of all possible linear ablations, no VT could be induced with up to 3 exstrastimuli except in 1 pt, in whom bundle branch reentrant (BBR)-VT was induced after ablation, and only that pt had recurrent BBR-VT during a mean follow up of 16 months. No pts had exacerbations of the cardiac function or BNP elevations after the ablation.
Conclusions Linear ablation of possible VT isthmuses was always accompanied with the elimination of most DPs that could be other targets of VT ablation. These findings might be the key to the very high success rate.