Ventricular remodeling after myocardial infarction is associated with a potential proarrhythmic substrate. However , the interplay between the structural and functional substrate for ventricular tachycardia (VT) maintenance is not completely understood. Here, we aimed to study the scar and fiber disorganization substrate associated with functional alterations during ventricular pacing and VT mapping.
Fourteen pigs with infarct-related substrate underwent state-of-the-art cardiac imaging and invasive mapping procedures to identify the functional and structural properties associated with abnormal wave-front propagation and VT maintenance. Further analysis include 8 pig's (males 100%, age 5 months [5, 6 months], weight 60.2 Kg [54.4, 64 Kg], LVEF 33.9% [30.8, 37.5%]) delineations of functional-relevant regions of interest for pacing deceleration zones(DZ) and VT circuit sites, as well as the conformation of fiber disorganization index(FDI) maps to quantify 3D regional structural disorganization differences in functional-relevant regions and scar related regions. The results show that deceleration zones during ventricular pacing and critical isthmus sites during VT mapping show similar underlying scar properties and myocardial fiber disorganization index values (0.23 [0.20, 0.27]) vs. 0.25 [0.21, 0.33], respectively, p=0.52), being these linked to heterogeneous scar regions. However, deceleration zones derived from one pacing location were not sufficient to identify critical VT isthmus sites with only 3.5% [0, 35.5%] of the VT ROIs overlapped with pacing DZ ROIs in animals, suggesting that pacing from single location will not be adequate for identifying all the myocardial regions that are linked to the maintenance of VT.