The Impact of Electrogram Type and Conduction Velocity Estimation Techniques on Assessments of Conduction Velocity During Ventricular Substrate Mapping

Conduction velocity (CV) mapping has the potential to identify critical regions of the ventricular substrate to target by ablation. However, it is unknown how electrogram modality and methodology affects CV estimauon. We aimed to test these effects in a control population for patients with structurally normal hearts and idiopathic ventricular ectopy. Electroanatomical contact mapping was performed using EnSite™ X (Abbott) with the Advisor HD Grid for patients with structurally normal hearts undergoing elective ventricular ectopy ablation. CV was assessed using four methods: 1. omnipolar wavespeed (Abbott); 2. local gradient estimation from the interpolated LAT field; 3. fitting a planar wavefront to LAT measurements; 4. fitting a circular wavefront and estimating CV. CV estimates were compared between methods. We analysed a total of 25 maps for 5 cases. Our results reveal than mean CV depends on CV estimation technique: e.g. for omnipolar recordings, wavespeed, Mean ± SD (m/s); $1.06\ \pm 3.36$; gradient; $0.62\ \pm 0.40$; fitting a planar wavefront; $0.94\ \pm 0.42$; fitting a circular wavefront; $0.93 \pm 0.90$. Median pointwise difference is also large between EGMs and across techniques. Thus, in structurally normal hearts, CV estimation technique has a large effect on CV maps calculated during ventricular substrate mapping.