Delineating Post-Infarct Ventricular Tachycardia Substrate with Dynamic Voltage Mapping in Areas of Omnipolar Vector Disarray

Background Defining post-infarct ventricular arrhythmic substrate is challenging with voltage mapping alone, though may be improved in combination with an activation map. Omnipolar Technology on the EnSite X system displays activation as vectors that can be superimposed onto a voltage map. Objective To optimise voltage map settings during ventricular tachycardia (VT) ablation, adjusting them dynamically using Omnipolar vectors. Methods Consecutive patients undergoing substrate mapping were retrospectively studied. We categorised Omni-vectors as “uniform” when pointing in one direction, or in “disarray” when pointing in multiple directions. We superimposed vectors onto voltage maps coloured purple in tissue >1.5mV, and the voltage settings were adjusted so uniform vectors appeared within purple voltages, a process termed “Dynamic Voltage Mapping” (DVM). Vectors in disarray appeared within red-blue lower voltages. Results 17 substrate maps were studied in 14 patients (mean age 63±13 years; mean LVEF 35±6%, median 4 (IQR 2-8.5) recent VT episodes). The DVM mean voltage threshold that differentiated tissue supporting uniform vectors from disarray was 0.27mV, ranging between patients from 0.18-0.50mV, with good inter-observer agreement (median difference: 0.00mV). We found that VT isthmus components, as well as sites of latest activation, isochronal crowding, and excellent pace-maps co-located with tissue along the DVM borderzone surrounding areas of disarray. Conclusion Dynamic Voltage Mapping, guided by areas of Omnipolar vector disarray, allows for individualised post-infarct ventricular substrate characterisation. Tissue bordering areas of disarray may harbour greater arrhythmogenic potential.