Characterization of Post-infarct Scars in a Porcine Model – A Combined Experimental and Theoretical Study

Arrhythmias are often associated with healing infarcts and could arise from the border zone of the scars. The main purpose of this work was to characterize the infarct scars using in vivo electro-anatomic CARTO maps (recorded in sinus rhythm) and high-resolution ex-vivo MR images in a porcine model of chronic infarct. The MR images were segmented into scar, peri-infarct and healthy ventricular tissue, and, in select slices, the results of segmentation were validated against histology. Further, the segmented volumes and associated fiber directions (derived from diffusion-weighted (DW) MRI as well as from synthetic models), were used as input to a simple two-variable mathematical model that calculates the propagation of depolarization waves and isochronal maps; and these isochronal maps were compared to the measured ones. We further correlated the size of the scar measured during the electrophysiology (EP) study with scar dimensions obtained from MRI using ex-vivo DW-MRI methods. Finally, we present preliminary results from a qualitative comparison between the scar delineation from ex vivo and in vivo MR images.