title: Role of first pass and delayed enhancement in assessment of segmental functional recovery after acute myocardial infarction.
abstract: OBJECTIVE
  Assessing myocardial viability is crucial in decision making and prognostic restratification after acute myocardial infarction (MI). A number of noninvasive imaging modalities have been employed in viability identification, but contrast-enhanced magnetic resonance (MR) imaging has been shown to be extremely accurate because of its transmural resolution and precise definition of microvascular obstruction. Our purpose was to assess functional recovery after acute MI, with special focus on the role of infarct transmurality and microvascular obstruction.
  
  
  METHODS
  Forty-six consecutive patients with first acute MI, reperfused by primary percutaneous transluminal coronary angioplasty (PTCA) (n=40) or fibrinolysis (n=6), underwent MR imaging within the first week to assess oedema, microvascular obstruction, function and viability and then again after 4-6 months to assess functional recovery and scar.
  
  
  RESULTS
  At first MR examination, postcontrast images were analysed according to three patterns, based on a combination of first-pass and delayed-enhancement data: pattern 1 (normal first pass and late hyperenhancement <50% thickness) identified viable myocardium, whereas pattern 2 (late hyperenhancement >50% thickness, with or without first-pass perfusion defect) and pattern 3 (perfusion defect at first pass and late hypoenhancement) recognised nonviable myocardium, with 93% sensitivity, 75% specificity, 92% positive predictive value and 78% negative predictive value for identifying viable tissue. Furthermore, by dividing pattern 2 into two subpatterns, 2A and 2B, based on absence or presence of microvascular obstruction in >50% transmural infarcts, we were able to better identify the segments without recovery or that were nonviable with a 1.39 relative risk of failed recovery.
  
  
  CONCLUSIONS
  After acute MI, not all infarcts with transmurality >50% can be considered nonviable; microvascular obstruction detected at first pass can help to better stratify these cases.
authors.affiliation: Unità di Risonanza Magnetica, Centro Oncologico Fiorentino, Via Attilio Ragionieri 101, 50119, Sesto Fiorentino, Italy. luiginatale@mac.com
authors.forename: L
authors.initials: L
authors.lastname: Natale
authors.forename: C
authors.initials: C
authors.lastname: Napolitano
authors.forename: A
authors.initials: A
authors.lastname: Bernardini
authors.forename: A
authors.initials: A
authors.lastname: Meduri
authors.forename: R
authors.initials: R
authors.lastname: Marano
authors.forename: A
authors.initials: A
authors.lastname: Lombardo
authors.forename: F
authors.initials: F
authors.lastname: Crea
authors.forename: L
authors.initials: L
authors.lastname: Bonomo
mesh_terms: D015906:Angioplasty, Balloon, Coronary; D003287:Contrast Media; D019786:Gadolinium DTPA; D006801:Humans; D008279:Magnetic Resonance Imaging; D009203:Myocardial Infarction / Q000175:diagnosis* / Q000503:physiopathology; D012680:Sensitivity and Specificity; D014022:Tissue Survival
chemical_list: D003287:Contrast Media; D019786:Gadolinium DTPA