title: Grade 3 ischemia on the admission electrocardiogram is associated with severe microvascular injury on cardiac magnetic resonance imaging after ST elevation myocardial infarction.
abstract: BACKGROUND
  Grade 3 ischemia during ST elevation myocardial infarction (STEMI) is defined as ST elevation with distortion of the terminal portion of the QRS on electrocardiogram (ECG). The aim of this study was to evaluate the effect of ischemic grade on cardiac magnetic resonance (CMR) imaging infarct characteristics such as infarct size, microvascular obstruction (MVO), intramyocardial hemorrhage (IMH), and myocardial salvage.
  
  
  METHODS
  Patients with STEMI treated with primary percutaneous coronary intervention had a 12-lead ECG on presentation for analysis of ischemic grade. Gadolinium-enhanced CMR imaging was performed within 7 days to assess infarct size, MVO, IMH, and myocardial salvage.
  
  
  RESULTS
  Of the 37 patients enrolled in the study, grade 3 ischemia was present in 32%. Those with grade 3 ischemia had higher peak troponin I levels (P = .013), more MVO (P < .001), more IMH (P < .001), larger infarct size (P = .025), and less myocardial salvage (P = .012). Regression analysis found that grade 3 ischemia, infarct size, and peak troponin I level were significantly associated with MVO and IMH.
  
  
  CONCLUSIONS
  Grade 3 ischemia on the admission ECG during STEMI is closely associated with the development of severe microvascular damage on CMR imaging.
authors.affiliation: Department of Cardiology, St George Hospital, Sydney, Australia. james.weaver@sesiahs.health.nsw.gov.au
authors.forename: James C
authors.initials: JC
authors.lastname: Weaver
authors.forename: David
authors.initials: D
authors.lastname: Rees
authors.forename: Ananth M
authors.initials: AM
authors.lastname: Prasan
authors.forename: David D
authors.initials: DD
authors.lastname: Ramsay
authors.forename: Maurits F
authors.initials: MF
authors.lastname: Binnekamp
authors.forename: Jane A
authors.initials: JA
authors.lastname: McCrohon
mesh_terms: D000368:Aged; D004562:Electrocardiography / Q000379:methods*; D005260:Female; D006801:Humans; D019028:Magnetic Resonance Imaging, Cine / Q000379:methods*; D008297:Male; D008833:Microcirculation; D055806:Microvessels / Q000473:pathology*; D008875:Middle Aged; D009203:Myocardial Infarction / Q000175:diagnosis* / Q000473:pathology*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013223:Statistics as Topic