The Efficacy of Isochronal 3D Mapping-Based Ablation of Ventricular Arrhythmia

Treatment of ventricular arrhythmias (VAs) commonly involves ablating sites showing electrograms with the earliest activity relative to the VA, but there is no threshold value for prematurity guaranteeing success. Ablation of sites with great prematurity can still result in failure.We hypothesized that isochronal map area (ISCA), derived from isochrones indicating electrogram prematurity, could help identify ablation targets in VA patients, as well as predict outcome. Specifically, we hypothesized that smaller ICSA for a given prematurity value would indicate a shallower arrhythmogenic focus leading to a higher likelihood of successful ablation.We studied ICSA in 29 patients (12 males, 57 [17-65] years old) undergoing VA ablation. The VAs originated from the right and left ventricles in 11 and 18 patients, respectively. The earliest activation site of the VAs, ECG morphology of sinus beats and premature ventricular complexes (PVCs), and ISCA of activation preceding PVCs were evaluated.RF ablation at the site showing earliest prematurity resulted in VA elimination in 21 patients (success group). The 5-ms ISCA was smaller in the success group than in the failure group (0.2 [0.1-0.6] versus 1.0 [0.8-1.5] cm², respectively; P < 0.01). No significant difference was noted in prematurity itself (36 [30-45] versus 30 [29-33] ms, respectively; P = 0.07). The cut-off value of the 5 ms ISCA for successful RF ablation was 0.7 cm² with 87.5% sensitivity and 85.6% specificity.Isochrones of activity preceding PVCs appear to contain information beyond prematurity values and may help dictate suitable areas for successful ablation of VAs.