Abstract 5689: In-vivo Image Characteristics of Myocardial Scars and Distribution of Sites with Late Potentials Determined by Magnetic Resonance and Electroanatomical Mapping in a Porcine Infarct Model
Myocardial scars harbor areas of slowed conduction are important in the pathogenesis of reentrant arrhythmias. The purpose of this study was to investigate the location and distribution of electrogram (EGM) sites with late potentials (LP) within a porcine model of myocardial infarction (MI). Contrast enhanced magnetic resonance imaging (CeMRI) was performed in pigs (n=3) 4 – 6 weeks post MI. High-density electroanatomic (EA) maps of the epicardial (epi) and endocardial (endo) surfaces were also obtianed using the NavX system. The CeMRI images were used to create a high-resolution three-dimensional (3D) myocardial scar map. EGM recordings were made at 2352 points (epi/endo: 1258/1094). LP, observed at 401 points (epi/endo: 247/154), were classified as; mid-diastolic LP (MDLP: an EGM to LP interval ≤300ms), late diastolic LP (LDLP: an EGM to LP interval >300ms), and continuous activation (CON: a series of >3 irregular spikes). The total number of segments with a transmural scar (TS) determined by 3D CeMRI correlated with the number of segments with a scar of <0.5mV [dense-scar (DS)] in the epi and endo as determined by the EA system according to a 17-segment model [TS(n) vs DS(n): 4.7±1.2 vs 5±1 p=NS]. LDLPs and CONs were more prominent in the DS areas of the epi [MDLP/LDLP/CON: 12(15%)/36(47%)/38(88%)] and endo [32(35%)/28(60%)/13(87%)] as determined by EA mapping (P<0.0001). These findings suggest that high density scar mapping method using the 3D CeMRI scar model guidance is a valid method for identifying potential non-transmural and transmural parts of a scar that could harbor critical isthmuses of ventricular tachycardias.