Detailed Analysis of Electrogram Peak Frequency to guide Ventricular Tachycardia Substrate Mapping.

Abstract

Differentiating near-field (NF) and far-field (FF) electrograms (EGMs) is crucial in identifying critical arrhythmogenic substrate during Ventricular Tachycardia (VT) ablation. A novel algorithm annotates NF fractionated signals enabling EGM Peak Frequency (PF) determination using wavelet transformation. This study evaluated the algorithms effectiveness in identifying critical components of the VT circuit during substrate mapping. A multicentre, international cohort undergoing VT ablation were investigated. VT activation maps were used to demarcate the isthmus zone (IZ). Offline analysis was performed to evaluate the diagnostic performance of low voltage area (LVA) PF substrate mapping. A total of 30 patients encompassing 198,935 EGMs were included. The IZ PF was significantly higher in sinus rhythm (SR) compared to right ventricular paced (RVp) substrate maps (234(195-294)Hz vs 197(166-220)Hz; p=0.010). Compared to LVA PF, the IZ PF was significantly higher in both SR and RVp substrate maps (AUC: 0.74 and 0.70, respectively). A LVA PF threshold of ≥200Hz was optimal in SR maps (sensitivity 69%; specificity 64%) and RVp maps (sensitivity 60%; specificity 64%) in identifying the VT isthmus. In amiodarone-treated patients (n=20), SR substrate map IZ PF was significantly lower (222(186-257)Hz vs 303(244-375)Hz, p=0.009) compared to amiodarone-naïve patients (n=10). The ≥200Hz LVA PF threshold resulted in an 80% freedom from VT with a trend towards reduced ablation lesions and radiofrequency times. LVA PF substrate mapping identifies critical components of the VT circuit with an optimal threshold of ≥200Hz. Isthmus PF is influenced by chronic amiodarone therapy with lower values observed during RV pacing.