title: Characterization of myocardial scars: electrophysiological imaging correlates in a porcine infarct model.
abstract: BACKGROUND
  Definition of myocardial scars as identified by electroanatomic mapping is integral to catheter ablation of ventricular tachycardia (VT). Myocardial imaging can also identify scars prior to ablation. However, the relationship between imaging and voltage mapping is not well characterized.
  
  
  OBJECTIVE
  The purpose of this study was to verify the anatomic location and heterogeneity of scars as obtained by electroanatomic mapping with contrast-enhanced MRI (CeMRI) and histopathology, and to characterize the distribution of late potentials in a chronic porcine infarct model.
  
  
  METHODS
  In vivo 3-dimensional cardiac CeMRI was performed in 5 infarcted porcine hearts. High-density electroanatomic mapping was used to generate epicardial and endocardial voltage maps. Scar surface area and position on CeMRI were then correlated with voltage maps. Locations of late potentials were subsequently identified. These were classified according to their duration and fractionation. All hearts underwent histopathological examination after mapping.
  
  
  RESULTS
  The total dense scar surface area and location on CeMRI correlated to the total epicardial and endocardial surface scar on electroanatomic maps. Electroanatomic mapping (average of 1,532 ± 480 points per infarcted heart) showed that fractionated late potentials were more common in dense scars (<0.50 mV) as compared with border zone regions (0.51 to 1.5 mV), and were more commonly observed on the epicardium.
  
  
  CONCLUSIONS
  In vivo, CeMRI can identify areas of transmural and nontransmural dense scars. Fractionated late diastolic potentials are more common on the epicardium than the endocardium in dense scar. These findings have implications for catheter ablation of VT and for targeting the delivery of future therapies to scarred regions.
authors.affiliation: UCLA Cardiac Arrhythmia Center, David Geffen School of Medicine at UCLA, Los Angeles, California, USA.
authors.forename: Shiro
authors.initials: S
authors.lastname: Nakahara
authors.forename: Marmar
authors.initials: M
authors.lastname: Vaseghi
authors.forename: Rafael J
authors.initials: RJ
authors.lastname: Ramirez
authors.forename: Carissa G
authors.initials: CG
authors.lastname: Fonseca
authors.forename: Chi K
authors.initials: CK
authors.lastname: Lai
authors.forename: J Paul
authors.initials: JP
authors.lastname: Finn
authors.forename: Aman
authors.initials: A
authors.lastname: Mahajan
authors.forename: Noel G
authors.initials: NG
authors.lastname: Boyle
authors.forename: Kalyanam
authors.initials: K
authors.lastname: Shivkumar
mesh_terms: D000818:Animals; D002921:Cicatrix / Q000209:etiology / Q000473:pathology* / Q000503:physiopathology; D004195:Disease Models, Animal; D022062:Electrophysiologic Techniques, Cardiac; D007091:Image Processing, Computer-Assisted; D019028:Magnetic Resonance Imaging, Cine / Q000379:methods*; D009203:Myocardial Infarction / Q000150:complications / Q000473:pathology / Q000503:physiopathology*; D009206:Myocardium / Q000473:pathology*; D013552:Swine