Ventricular substrate characteristics using omnipolar technology-derived vector disarray and peak frequency

Abstract Background Three-dimensional electroanatomic mapping and ablation of ventricular tachycardias (VT) is a complex process that integrates data from multiple procedural steps, including substrate and activation mapping. Purpose To streamline diagnostic and therapeutic interventions, we applied the omnipolar near-field technology algorithm, with the goal of integrating it into the study of low-voltage areas, deceleration zones (DZs), areas of vector disarray (in sinus rhythm, SR), and critical VT isthmus sites. Methods In this single-center retrospective study, three-dimensional electroanatomic maps in SR of 35 patients (August 2023 to August 2024) were analysed. Substrate analysis focused on identifying low-voltage areas, late potentials, local abnormal ventricular activities (LAVAs), and DZs. Procedures were performed using the EnSite X Cardiac Mapping System (Abbott) with the Advisor HD Grid Mapping Catheter (Abbott). Radiofrequency lesions were delivered when clinically indicated. To quantify vector disarray, we analysed low voltage areas (range 0.04-1.50 mV) displaying omnipolar vectors, and the percentage of disarrayed vectors was calculated manually. Maps were compared via emphasis maps, integrating information from VT and SR maps. Results Over a 12-month period, 10 patients (5 female) underwent transcatheter ventricular mapping procedures for diagnostic purposes, and 25 patients (2 female) underwent VT ablation. Median age was 70 (IQR 54-74) years, with 19 (55.29%) patients with a history of ischemic heart disease. The primary procedure indications were electrical storm in 12 (34.29%), and sustained VT in 13 (37.14%) patients. The approach was endocardial in 30 patients, epicardial in 2, and combined endo-epicardial in 3 patients. The median highest peak frequency (PF) in the SR substrate maps within low-voltage areas was 280 (250-315) Hz. Median vector disarray was 60.27% (51.7-67.9), without significant differences between ischaemic and non-ischaemic cardiomyopathies (p=0.070). Low-voltage areas of VT interest displayed higher peak frequencies and greater vector disarray. Regions with PF above 250 Hz would overlap with chaotic vector areas and low-voltage areas in the majority of patients (82.4% and 85.3% respectively). Among patients with and without area overlap, there were no statistically significant differences in disease type, vector disarray percentage, age, and LVEF, while patients with overlapping areas had significantly larger high-frequency regions (p=0.005 and p=0.006, respectively). Conclusion During sinus rhythm, localisation of areas with increased PF and chaotic and low-voltage areas is frequent, and may aid in the identification of colliding wavefronts in low-voltage tissues during SR, thus characterising a possible arrhythmic substrate. Future studies are needed to investigate its potential advantages to limit the requirement for VT activation mapping.Characteristics of the study population OTNF and vector disarray in SR and VT