Pranav Bhagirath

191 Feasibility and Accuracy of Cardiac Magnetic Resonance Imaging-Based Whole-Heart Inverse Potential Mapping of Sinus Rhythm and Idiopathic Ventricular Foci INTRODUCTION Inverse potential mapping (IPM) allows for non-invasive reconstruction of epicardial activation patterns. The most frequently used IPM method is based on a homogeneous volume conductor model (VCM) constructed from computed tomography (CT) images (1) . This technique is increasingly being applied for analysis of idiopathic ventricular foci and guidance of catheter ablation (2, 3) . Although clinically useful, there are important limitations of this CT based approach. The most important limitation besides the exposure to radiation and associated risk of malignancies (4) , is the inability to characterize tissue in detail. Magnetic resonance imaging (MRI) does not have these limitations and is considered the gold standard for tissue characterization, in particular for edema and fibrosis. Although most publications underscore the fact that both CT and MRI can be used, MRI is less frequently utilized for IPM (5-7) . In addition, the use of a homogeneous VCM could also be considered a limitation since it may not appropriately incorporate the effects of specific tissue conductivity characteristics such as from the lungs (i.e. inhomogeneous conditions) (8) . This study investigated the feasibility of whole-heart IPM using a VCM derived from MRI. The clinical applicability of this approach was evaluated in healthy volunteers and patients with idiopathic ventricular foci. In addition, the influence of tissue impedance on the results of IPM was studied using two different VCM’s. A homogeneous thoracic VCM (Model 1) was compared to an inhomogeneous VCM where in addition to thoracic impedance, the resistance value of the lungs was included (Model 2). METHODS Patient Population The study population consisted of 3 healthy volunteers and 8 patients with symptomatic or therapy resistant premature ventricular contractions (PVC). The study complied with the declaration of Helsinki and received approval from the local ethical committee (METC Zuidwest Holland study number NL38156.098.11) and the institutional scientific board. Written informed consent was obtained from the study subjects.