title: Contractile reserve and contrast uptake pattern by magnetic resonance imaging and functional recovery after reperfused myocardial infarction.
abstract: OBJECTIVE
  We hypothesized that contrast-enhanced and dobutamine tagged magnetic resonance imaging (MRI) could investigate microvascular integrity and contractile reserve of reperfused myocardial infarction (MI) in one examination.
  
  
  BACKGROUND
  In reperfused MI, microvascular integrity and contractile reserve are important determinants of functional recovery.
  
  
  METHODS
  Twenty-three patients with a reperfused first MI were studied. On day 3+/-1 after MI, patients underwent tagged MRI at baseline and during infusion of 5 and 10 microg/kg/min of dobutamine followed by contrast-enhanced MRI (first pass and delayed imaging) after a bolus infusion of gadolinium-diethylenetriaminepenta-acetic acid. Tagged MRI was performed 9+/-1 weeks later (follow-up). Eighty-four transmural regions with hyperenhancement on delayed contrast-enhanced images were defined as COMB (first pass hypoenhancement) or HYPER (normal first pass signal enhancement). Percent circumferential segment shortening was measured within the subendocardium and subepicardum of each region of HYPER or COMB at baseline, peak dobutamine and follow-up.
  
  
  RESULTS
  Shortening improved in COMB regions from 4+/-1% at baseline to 10+/-1% at peak dobutamine and 10+/-1% at follow-up, respectively (p<0.0003 vs. baseline for both). The HYPER regions likewise improved from 10+/-1% at baseline to 16+/-1% and 17+/-1%, respectively (p<0.0004 vs. baseline for both). Function within COMB regions was less than that of HYPER at baseline, peak dobutamine and follow-up (p<0.0003 for all).
  
  
  CONCLUSIONS
  Dobutamine magnetic resonance tagging and contrast enhanced MRI are complementary in assessing functional recovery after reperfused MI. Regions of delayed contrast hyperenhancement demonstrate both contractile reserve and late functional recovery. However, if these regions demonstrate first pass contrast hypoenhancement, they are associated with greater myocardial damage.
authors.affiliation: Department of Medicine, University of Virginia Health System, Charlottesville 22908, USA. ckramer@virginia.edu
authors.forename: C M
authors.initials: CM
authors.lastname: Kramer
authors.forename: W J
authors.initials: WJ
authors.lastname: Rogers
authors.forename: S
authors.initials: S
authors.lastname: Mankad
authors.forename: T M
authors.initials: TM
authors.lastname: Theobald
authors.forename: D L
authors.initials: DL
authors.lastname: Pakstis
authors.forename: Y L
authors.initials: YL
authors.lastname: Hu
mesh_terms: D002316:Cardiotonic Agents; D004280:Dobutamine; D005260:Female; D006801:Humans; D007089:Image Enhancement; D007091:Image Processing, Computer-Assisted; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D009200:Myocardial Contraction; D009203:Myocardial Infarction / Q000000981:diagnostic imaging* / Q000628:therapy; D015425:Myocardial Reperfusion; D014463:Ultrasonography; D015646:Ventriculography, First-Pass
chemical_list: D002316:Cardiotonic Agents; D004280:Dobutamine