title: Differentiation of subendocardial and transmural infarction using two-dimensional strain rate imaging to assess short-axis and long-axis myocardial function.
abstract: OBJECTIVE
  This study sought to differentiate the transmural extent of infarction (TME) by assessment of the short-axis and long-axis function of the left ventricle (LV) using 2-dimensional (2D) strain.
  
  
  BACKGROUND
  The differentiation of subendocardial infarction from transmural infarction has significant prognostic and clinical implications.
  
  
  METHODS
  Contrast-enhanced magnetic resonance imaging (CE-MRI) and dobutamine stress echocardiography (DBE) were performed in 80 patients (age 63 +/- 10 years) with chronic ischemic LV dysfunction. Myocardial function was assessed in the short axis at the midventricular level using peak strain rate (SR) and strain (S) in circumferential and radial dimensions, and was assessed in the long axis using longitudinal SR and S. Wall motion analysis was performed during DBE to assess for contractile reserve.
  
  
  RESULTS
  Transmural infarct segments had lower circumferential S (-10.7 +/- 6.3) and SR (-1.0 +/- 0.4) than subendocardial infarcts (S: -15.4 +/- 7.0, p < 0.0001; SR: -1.4 +/- 0.8, p = 0.02) and normal myocardium (S: p < 0.0001; SR: p < 0.0001). Transmural and subendocardial infarct segments had similar radial S and SR. Subendocardial infarct segments showed significant reduction of longitudinal S (-13.2 +/- 5.6) and SR (-0.91 +/- 0.45) compared with normal myocardium (S: -17.8 +/- 5.4, p < 0.0001; SR: -1.1 +/- 0.41, p < 0.0001), but there were no significant differences between subendocardial and transmural infarct segments (p = 0.09). Wall motion analysis by DBE could not identify subendocardial infarction on CE-MRI (TME 1% to 50%: DBE scar 38%, DBE viable 38%, DBE ischemic 24%, p = NS).
  
  
  CONCLUSIONS
  The combined assessment of long-axis and short-axis function using 2D strain may be used to identify TME.
authors.affiliation: University of Queensland, Brisbane, Australia.
authors.forename: Jonathan
authors.initials: J
authors.lastname: Chan
authors.forename: Lizelle
authors.initials: L
authors.lastname: Hanekom
authors.forename: Chiew
authors.initials: C
authors.lastname: Wong
authors.forename: Rodel
authors.initials: R
authors.lastname: Leano
authors.forename: Goo-Yeong
authors.initials: GY
authors.lastname: Cho
authors.forename: Thomas H
authors.initials: TH
authors.lastname: Marwick
mesh_terms: D000368:Aged; D003287:Contrast Media; D003937:Diagnosis, Differential; D004452:Echocardiography; D025401:Echocardiography, Stress; D005240:Feasibility Studies; D005260:Female; D006321:Heart / Q000503:physiopathology*; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D009203:Myocardial Infarction / Q000145:classification* / Q000175:diagnosis* / Q000503:physiopathology; D015203:Reproducibility of Results
chemical_list: D003287:Contrast Media