title: Infarct healing is a dynamic process following acute myocardial infarction.
abstract: BACKGROUND
  The role of infarct size on left ventricular (LV) remodeling in heart failure after an acute ST-segment elevation myocardial infarction (STEMI) is well recognized. Infarct size, as determined by cardiovascular magnetic resonance (CMR), decreases over time. The amount, rate, and duration of infarct healing are unknown.
  
  
  METHODS
  A total of 66 patients were prospectively enrolled after reperfusion for an acute STEMI. Patients underwent a CMR evaluation within 1 week, 4 months, and 14 months after STEMI.
  
  
  RESULTS
  Mean infarct sizes for the 66 patients at baseline (acute necrosis), early follow-up (early scar), and late follow-up (late scar) were 25 ± 17 g, 17 ± 12 g, and 15 ± 11 g, respectively. Patients were stratified in tertiles, based on infarct size, with the largest infarcts having the greatest absolute decrease in mass at early and late scar. The percent reduction of infarct mass was independent of initial infarct size. There was an 8 g or 32% decrease in infarct mass between acute necrosis and early scar (p < 0.01) with a 2 g or 12% additional decrease in infarct mass between early and late scar (p < 0.01).
  
  
  CONCLUSIONS
  Infarct healing is a continuous process after reperfusion for STEMI, with greatest reduction in infarct size in the first few months. The dynamic nature of infarct healing through the first year after STEMI indicates that decisions based on infarct size, and interventions to reduce infarct size, must take into consideration the time frame of measurement.
authors.affiliation: Department of Medicine, Division of Cardiology, Bluhm Cardiovascular Institute, Northwestern University Feinberg School of Medicine, Northwestern Memorial Hospital, 676 Saint Clair St, Suite 600, Chicago, IL 60611, USA.
authors.forename: Sean D
authors.initials: SD
authors.lastname: Pokorney
authors.forename: José F
authors.initials: JF
authors.lastname: Rodriguez
authors.forename: José T
authors.initials: JT
authors.lastname: Ortiz
authors.forename: Daniel C
authors.initials: DC
authors.lastname: Lee
authors.forename: Robert O
authors.initials: RO
authors.lastname: Bonow
authors.forename: Edwin
authors.initials: E
authors.lastname: Wu
mesh_terms: D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D019028:Magnetic Resonance Imaging, Cine / Q000379:methods*; D008297:Male; D008875:Middle Aged; D009203:Myocardial Infarction / Q000175:diagnosis* / Q000503:physiopathology; D009206:Myocardium / Q000473:pathology*; D011379:Prognosis; D011446:Prospective Studies; D016277:Ventricular Function, Left / Q000502:physiology*; D020257:Ventricular Remodeling