title: Noninvasive identification of epicardial ventricular tachycardia substrate by magnetic resonance-based signal intensity mapping.
abstract: BACKGROUND
  Endo-epicardial substrate ablation reduces ventricular tachycardia (VT) recurrences; however, not all patients in whom the epicardium is explored have a VT substrate. Contrast-enhanced magnetic resonance imaging (ceMRI) is used to characterize VT substrate after myocardial infarction.
  
  
  OBJECTIVE
  The purpose of this study was to determine if epicardial VT substrate can be identified noninvasively by ceMRI-based endo-epicardial signal intensity (SI) mapping.
  
  
  METHODS
  Myocardial infarction was induced in 31 pigs. Four or 16 weeks later, ceMRI was obtained, and the averaged subendocardial and subepicardial SIs were projected onto 3-dimensional endocardial and epicardial shells in which dense scar, heterogeneous tissue (HT), and normal tissue were differentiated. An HT channel was defined as a corridor of HT surrounded by dense scar and connected to normal tissue. A "patchy" scar pattern was defined as the presence of at least 3 dense scar islets surrounded by HT forming ≥2 HT channels. Electrophysiologic study was performed after ceMRI.
  
  
  RESULTS
  Thirty-three different sustained monomorphic VTs (291 ± 49 ms) were induced in 25 pigs. Mid-diastolic electrograms were recorded in the endocardium (endocardial VT) in 17 and in the epicardium (epicardial VT) in 13. Epicardial SI mapping showed that scar area was similar in animals with and without epicardial VT (24 ± 6 cm2 vs. 25 ± 12 cm2), but HT covered a higher surface of the epicardial scar in animals with VT (76 ± 6% vs. 61 ± 10%, P = .03). A patchy scar pattern was observed in all animals with epicardial VT but only in 3 animals without VT (P < .001).
  
  
  CONCLUSIONS
  CeMRI-based SI mapping allows identification of the epicardial VT substrate.
authors.affiliation: Hospital General Universitario Gregorio Marañón, Madrid, Spain. Electronic address: arenal@secardiologia.es.
authors.forename: Angel
authors.initials: A
authors.lastname: Arenal
authors.affiliation: Hospital General Universitario Gregorio Marañón, Madrid, Spain.
authors.forename: Esther
authors.initials: E
authors.lastname: Pérez-David
authors.affiliation: Hospital General Universitario Gregorio Marañón, Madrid, Spain.
authors.forename: Pablo
authors.initials: P
authors.lastname: Avila
authors.affiliation: Centro de Cirugía de Mínima Invasión Jesús Usón, Cáceres, Spain.
authors.forename: Javier
authors.initials: J
authors.lastname: Fernández-Portales
authors.affiliation: Centro de Cirugía de Mínima Invasión Jesús Usón, Cáceres, Spain.
authors.forename: Verónica
authors.initials: V
authors.lastname: Crisóstomo
authors.affiliation: Centro de Cirugía de Mínima Invasión Jesús Usón, Cáceres, Spain.
authors.forename: Claudia
authors.initials: C
authors.lastname: Báez
authors.affiliation: Centro de Cirugía de Mínima Invasión Jesús Usón, Cáceres, Spain.
authors.forename: Javier
authors.initials: J
authors.lastname: Jiménez-Candil
authors.affiliation: Universidad Politécnica de Madrid and CIBER-BBN, Spain.
authors.forename: José L
authors.initials: JL
authors.lastname: Rubio-Guivernau
authors.affiliation: Universidad Politécnica de Madrid and CIBER-BBN, Spain.
authors.forename: María J
authors.initials: MJ
authors.lastname: Ledesma-Carbayo
authors.affiliation: Hospital General Universitario Gregorio Marañón, Madrid, Spain.
authors.forename: Gerard
authors.initials: G
authors.lastname: Loughlin
authors.affiliation: Hospital General Universitario Gregorio Marañón, Madrid, Spain.
authors.forename: Javier
authors.initials: J
authors.lastname: Bermejo
authors.affiliation: Centro de Cirugía de Mínima Invasión Jesús Usón, Cáceres, Spain.
authors.forename: Francisco M
authors.initials: FM
authors.lastname: Sánchez-Margallo
authors.affiliation: Hospital General Universitario Gregorio Marañón, Madrid, Spain.
authors.forename: Francisco
authors.initials: F
authors.lastname: Fernández-Avilés
mesh_terms: D000818:Animals; D018780:Body Surface Potential Mapping / Q000379:methods; D004195:Disease Models, Animal; D004562:Electrocardiography; D056149:Epicardial Mapping / Q000379:methods*; D019028:Magnetic Resonance Imaging, Cine / Q000379:methods*; D010496:Pericardium / Q000503:physiopathology*; D012008:Recurrence; D013552:Swine; D017180:Tachycardia, Ventricular / Q000175:diagnosis* / Q000503:physiopathology
keywords: Arrhythmogenic substrate; Epicardium; Magnetic resonance imaging; Ventricular tachycardia