title: Infarct tissue heterogeneity by magnetic resonance imaging identifies enhanced cardiac arrhythmia susceptibility in patients with left ventricular dysfunction.
abstract: BACKGROUND
  The extent of the peri-infarct zone by magnetic resonance imaging (MRI) has been related to all-cause mortality in patients with coronary artery disease. This relationship may result from arrhythmogenesis in the infarct border. However, the relationship between tissue heterogeneity in the infarct periphery and arrhythmic substrate has not been investigated. In the present study, we quantify myocardial infarct heterogeneity by contrast-enhanced MRI and relate it to an electrophysiological marker of arrhythmic substrate in patients with left ventricular (LV) systolic dysfunction undergoing prophylactic implantable cardioverter defibrillator placement.
  
  
  RESULTS
  Before implantable cardioverter defibrillator implantation for primary prevention of sudden cardiac death, 47 patients underwent cine and contrast-enhanced MRI to measure LV function, volumes, mass, and infarct size. A method for quantifying the heterogeneous infarct periphery and the denser infarct core is described. MRI indices were related to inducibility of sustained monomorphic ventricular tachycardia during electrophysiological or device testing. For the noninducible versus inducible patients, LV ejection fraction (30+/-10% versus 29+/-7%, P=0.79), LV end-diastolic volume (220+/-70 versus 228+/-57 mL, P=0.68), and infarct size by standard contrast-enhanced MRI definitions (P=NS) were similar. Quantification of tissue heterogeneity at the infarct periphery was strongly associated with inducibility for monomorphic ventricular tachycardia (noninducible versus inducible: 13+/-9 versus 19+/-8 g, P=0.015) and was the single significant factor in a stepwise logistic regression.
  
  
  CONCLUSIONS
  Tissue heterogeneity is present and quantifiable within human infarcts. More extensive tissue heterogeneity correlates with increased ventricular irritability by programmed electrical stimulation. These findings support the hypothesis that anatomic tissue heterogeneity increases susceptibility to ventricular arrhythmias in patients with prior myocardial infarction and LV dysfunction.
authors: Division of Cardiology, Department of Medicine, Johns Hopkins University, Baltimore, MD, USA.
authors: André
authors: A
authors: Schmidt
authors: Clerio F
authors: CF
authors: Azevedo
authors: Alan
authors: A
authors: Cheng
authors: Sandeep N
authors: SN
authors: Gupta
authors: David A
authors: DA
authors: Bluemke
authors: Thomas K
authors: TK
authors: Foo
authors: Gary
authors: G
authors: Gerstenblith
authors: Robert G
authors: RG
authors: Weiss
authors: Eduardo
authors: E
authors: Marbán
authors: Gordon F
authors: GF
authors: Tomaselli
authors: João A C
authors: JA
authors: Lima
authors: Katherine C
authors: KC
authors: Wu
mesh_terms: D001145:Arrhythmias, Cardiac / Q000175:diagnosis* / Q000209:etiology / Q000628:therapy; D017147:Defibrillators, Implantable; D004198:Disease Susceptibility / Q000175:diagnosis; D022062:Electrophysiologic Techniques, Cardiac; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods*; D019028:Magnetic Resonance Imaging, Cine; D008297:Male; D008875:Middle Aged; D009203:Myocardial Infarction / Q000150:complications / Q000175:diagnosis* / Q000503:physiopathology; D011237:Predictive Value of Tests; D017180:Tachycardia, Ventricular / Q000175:diagnosis / Q000209:etiology / Q000628:therapy; D018487:Ventricular Dysfunction, Left / Q000150:complications / Q000503:physiopathology*