title: Time elapsed after contrast injection is crucial to determine infarct transmurality and myocardial functional recovery after an acute myocardial infarction.
abstract: BACKGROUND
  In acute myocardial infarction (MI), late Gadolinium enhancement (LGE) has been proposed to include the infarcted myocardium and area at risk. However, little information is available on the optimal timing after contrast injection to differentiate these 2 areas. Our aim was to determine in acute and chronic MI whether imaging time after contrast injection influences the LGE size that better predicts infarct size and functional recovery.
  
  
  METHODS
  Subjects were evaluated by cardiovascular magnetic resonance (CMR) the first week (n = 60) and 3 months (n = 47) after a percutaneously revascularized STEMI. Inversion-recovery single-shot (ss-IR) imaging was acquired at multiple time points following contrast administration and compared to segmented inversion-recovery (seg-IR) sequences. Inversion time was properly adjusted and images were blinded, randomized and measured for LGE volumes.
  
  
  RESULTS
  In acute MI, LGE volume decreased over several minutes (p = 0.005) with the greatest volume occurring at 3 minutes and the smallest at 25 minutes post-contrast injection; however, LGE volume remained constant over time in chronic MI (p = 0.886). Depending on the imaging time, in acute phase, a change in the transmurality index was also observed. A transmural infarction (>75%) at 25 minutes better predicted the absence of improvement in the wall motion score index (WMSI), a higher increase in left ventricular volumes and a lower ejection fraction compared to 10 minutes.
  
  
  CONCLUSIONS
  A change was observed in LGE volume in the minutes following contrast administration in acute but not in chronic MI. Infarct transmurality 25 minutes post-contrast injection better predicted infarct size and functional recovery at follow-up.
authors.affiliation: Department of Cardiology, Institut de Recerca (VHIR), Hospital Universitari Vall d´Hebron, Universitat Autònoma de Barcelona, Barcelona, Spain. jfrodriguezpalomares@gmail.com.|Department of Medicine, Division of Cardiology, Bluhm Cardiovascular Institute, Northwestern Memorial Hospital, Northwestern University Feinberg School of Medicine, Chicago, IL, USA. jfrodriguezpalomares@gmail.com.|Department of Cardiology, Hospital Universitari Vall d'Hebron, Paseo Vall d'Hebron 119-129, Barcelona, 08035, Spain. jfrodriguezpalomares@gmail.com.
authors.forename: José F
authors.initials: JF
authors.lastname: Rodríguez-Palomares
authors.affiliation: Department of Medicine, Division of Cardiology, Bluhm Cardiovascular Institute, Northwestern Memorial Hospital, Northwestern University Feinberg School of Medicine, Chicago, IL, USA.
authors.forename: José T
authors.initials: JT
authors.lastname: Ortiz-Pérez
authors.affiliation: Department of Medicine, Division of Cardiology, Bluhm Cardiovascular Institute, Northwestern Memorial Hospital, Northwestern University Feinberg School of Medicine, Chicago, IL, USA.|Departments of Medicine and Radiology, Northwestern University Feinberg School of Medicine, Chicago, IL, USA.
authors.forename: Daniel C
authors.initials: DC
authors.lastname: Lee
authors.affiliation: Department of Medicine, Division of Cardiology, Bluhm Cardiovascular Institute, Northwestern Memorial Hospital, Northwestern University Feinberg School of Medicine, Chicago, IL, USA.|Bristol Heart Institute, NIHR Bristol Cardiovascular Biomedical Research Unit, University of Bristol, Bristol, UK.
authors.forename: Chiara
authors.initials: C
authors.lastname: Bucciarelli-Ducci
authors.affiliation: Department of Medicine, Division of Cardiology, Bluhm Cardiovascular Institute, Northwestern Memorial Hospital, Northwestern University Feinberg School of Medicine, Chicago, IL, USA.
authors.forename: Paula
authors.initials: P
authors.lastname: Tejedor
authors.affiliation: Department of Medicine, Division of Cardiology, Bluhm Cardiovascular Institute, Northwestern Memorial Hospital, Northwestern University Feinberg School of Medicine, Chicago, IL, USA.
authors.forename: Robert O
authors.initials: RO
authors.lastname: Bonow
authors.affiliation: Department of Medicine, Division of Cardiology, Bluhm Cardiovascular Institute, Northwestern Memorial Hospital, Northwestern University Feinberg School of Medicine, Chicago, IL, USA.|Departments of Medicine and Radiology, Northwestern University Feinberg School of Medicine, Chicago, IL, USA.
authors.forename: Edwin
authors.initials: E
authors.lastname: Wu
mesh_terms: D000368:Aged; D003287:Contrast Media / Q000008:administration & dosage* / Q000493:pharmacokinetics; D005260:Female; D019786:Gadolinium DTPA / Q000008:administration & dosage* / Q000493:pharmacokinetics; D006801:Humans; D007267:Injections; D019028:Magnetic Resonance Imaging, Cine; D008297:Male; D008875:Middle Aged; D009203:Myocardial Infarction / Q000175:diagnosis* / Q000473:pathology / Q000503:physiopathology; D009206:Myocardium / Q000473:pathology*; D011237:Predictive Value of Tests; D011379:Prognosis; D020127:Recovery of Function; D015203:Reproducibility of Results; D059629:Signal-To-Noise Ratio; D013318:Stroke Volume; D013997:Time Factors; D016277:Ventricular Function, Left
chemical_list: D003287:Contrast Media; D019786:Gadolinium DTPA