Pranav Bhagirath

193 Feasibility and Accuracy of Cardiac Magnetic Resonance Imaging-Based Whole-Heart Inverse Potential Mapping of Sinus Rhythm and Idiopathic Ventricular Foci anatomical mapping (EAM) system (Ensite Velocity 3.0, St. Jude Medical). An EAM was created using the roving catheter. Respiratory compensation was set to automatic. No field scaling was performed. If no spontaneous PVC’s were present, isoproterenol and/or pacing maneuvers were used to provoke PVC’s. After the focus location was identified, targeted ablation was performed using a standard 4-mm non irrigated ablation catheter with power delivery up to 50W and a temperature limitation of 50ºC. Subsequently, the site of ablation was marked on the EAM system. Comparison of focus localization Following the ablation procedure, the ectopic PVC focus location, as identified on the IPM, was compared with the site of ablation, as specified on the EAM (gold-standard). For this purpose, two experienced operators (PB and HR) independently identified the foci on IPM and EAM to provide a measure of inter-observer variability. This resulted in three different datasets describing the focus localization as the x, y and z coordinate: 1) IPM utilizing the homogeneous model (dataset 1), 2) IPM utilizing the inhomogeneousmodel (dataset 2) and 3) EAM (dataset 3). Subsequently, the Pythagoras theorem for 3-dimensional coordinate vectors, where the distance between two points is equal to the square root of the sum of the squared coordinate differences, was used to calculate the differences between coordinate dataset 1 and 3, and coordinate dataset 2 and 3. Statistical analysis Statistical analysis was performed using IBM SPSS Statistics (Version 22.0). Continuous variableswereexpressedasmean±standarddeviationor usingmedianand interquartile range. Localization errors between the two VCM were compared using the Wilcoxon Signed-Rank test. The intra-class correlation coefficient (ICC) was used to analyze the inter-observer agreement. A p < 0.05 was considered to be statistically significant. RESULTS Study population Baseline characteristics of the 3 volunteers and 8 patients (N=11) are provided in table 1 . All volunteers had normal electrocardiograms. In both volunteers and patients, structural heart disease was excluded based on the MRI examination.