title: Magnetic resonance assessment of the substrate for inducible ventricular tachycardia in nonischemic cardiomyopathy.
abstract: BACKGROUND
  Patients with left ventricular dysfunction have an elevated risk of sudden cardiac death. However, the substrate for ventricular arrhythmia in patients with nonischemic cardiomyopathy remains poorly understood. We hypothesized that the distribution of scar identified by MRI is predictive of inducible ventricular tachycardia.
  
  
  RESULTS
  Short-axis cine steady-state free-precession and postcontrast inversion-recovery gradient-echo MRI sequences were obtained before electrophysiological study in 26 patients with nonischemic cardiomyopathy. Left ventricular ejection fraction was measured from end-diastolic and end-systolic cine images. The transmural extent of scar as a percentage of wall thickness (percent scar transmurality) in each of 12 radial sectors per slice was calculated in all myocardial slices. The percentages of sectors with 1% to 25%, 26% to 50%, 51% to 75%, and 76% to 100% scar transmurality were determined for each patient. Predominance of scar distribution involving 26% to 75% of wall thickness was significantly predictive of inducible ventricular tachycardia and remained independently predictive in the multivariable model after adjustment for left ventricular ejection fraction (odds ratio, 9.125; P=0.020).
  
  
  CONCLUSIONS
  MR assessment of scar distribution can identify the substrate for inducible ventricular tachycardia and may identify high-risk patients with nonischemic cardiomyopathy currently missed by ejection fraction criteria.
authors.affiliation: Department of Medicine/Cardiology, Johns Hopkins Hospital, Baltimore, MD 21287, USA. snazari1@jhmi.edu
authors.forename: Saman
authors.initials: S
authors.lastname: Nazarian
authors.forename: David A
authors.initials: DA
authors.lastname: Bluemke
authors.forename: Albert C
authors.initials: AC
authors.lastname: Lardo
authors.forename: Menekhem M
authors.initials: MM
authors.lastname: Zviman
authors.forename: Stanley P
authors.initials: SP
authors.lastname: Watkins
authors.forename: Timm L
authors.initials: TL
authors.lastname: Dickfeld
authors.forename: Glenn R
authors.initials: GR
authors.lastname: Meininger
authors.forename: Ariel
authors.initials: A
authors.lastname: Roguin
authors.forename: Hugh
authors.initials: H
authors.lastname: Calkins
authors.forename: Gordon F
authors.initials: GF
authors.lastname: Tomaselli
authors.forename: Robert G
authors.initials: RG
authors.lastname: Weiss
authors.forename: Ronald D
authors.initials: RD
authors.lastname: Berger
authors.forename: João A C
authors.initials: JA
authors.lastname: Lima
authors.forename: Henry R
authors.initials: HR
authors.lastname: Halperin
mesh_terms: D009202:Cardiomyopathies / Q000473:pathology*; D016757:Death, Sudden, Cardiac; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008279:Magnetic Resonance Imaging / Q000379:methods*; D009206:Myocardium / Q000473:pathology; D018487:Ventricular Dysfunction, Left / Q000473:pathology*