title: Magnetic resonance imaging-defined areas of microvascular obstruction after acute myocardial infarction represent microvascular destruction and haemorrhage.
abstract: OBJECTIVE
  Lack of gadolinium-contrast wash-in on first-pass perfusion imaging, early gadolinium-enhanced imaging, or late gadolinium-enhanced (LGE) cardiovascular magnetic resonance (CMR) imaging after revascularized ST-elevation myocardial infarction (STEMI) is commonly referred to as microvascular obstruction (MVO). Additionally, T2-weighted imaging allows for the visualization of infarct-related oedema and intramyocardial haemorrhage (IMH) within the infarction. However, the exact histopathological correlate of the contrast-devoid core and its relation to IMH is unknown.
  
  
  RESULTS
  In eight Yorkshire swine, the circumflex coronary artery was occluded for 75 min by a balloon catheter. After 7 days, CMR with cine imaging, T2-weighted turbospinecho, and LGE was performed. Cardiovascular magnetic resonance images were compared with histological findings after phosphotungstic acid-haematoxylin and anti-CD31/haematoxylin staining. These findings were compared with CMR findings in 27 consecutive PCI-treated STEMI patients, using the same scanning protocol. In the porcine model, the infarct core contained extensive necrosis and erythrocyte extravasation, without intact vasculature and hence, no MVO. The surrounding-gadolinium-enhanced-area contained granulation tissue, leucocyte infiltration, and necrosis with morphological intact microvessels containing microthrombi, without erythrocyte extravasation. Areas with IMH (median size 1.92 [0.36-5.25] cm(3)) and MVO (median size 2.19 [0.40-4.58] cm(3)) showed close anatomic correlation [intraclass correlation coefficient (ICC) 0.85, r = 0.85, P = 0.03]. Of the 27 STEMI patients, 15 had IMH (median size 6.60 [2.49-9.79] cm(3)) and 16 had MVO (median size 4.31 [1.05-7.57] cm(3)). Again, IMH and MVO showed close anatomic correlation (ICC 0.87, r = 0.93, P < 0.001).
  
  
  CONCLUSIONS
  The contrast-devoid core of revascularized STEMI contains extensive erythrocyte extravasation with microvascular damage. Attenuating the reperfusion-induced haemorrhage may be a novel target in future adjunctive STEMI treatment.
authors.affiliation: Department of Cardiology, VU University Medical Center, Amsterdam, the Netherlands.
authors.forename: Lourens F H J
authors.initials: LF
authors.lastname: Robbers
authors.forename: Elise S
authors.initials: ES
authors.lastname: Eerenberg
authors.forename: Paul F A
authors.initials: PF
authors.lastname: Teunissen
authors.forename: Matthijs F
authors.initials: MF
authors.lastname: Jansen
authors.forename: Maurits R
authors.initials: MR
authors.lastname: Hollander
authors.forename: Anton J G
authors.initials: AJ
authors.lastname: Horrevoets
authors.forename: Paul
authors.initials: P
authors.lastname: Knaapen
authors.forename: Robin
authors.initials: R
authors.lastname: Nijveldt
authors.forename: Martijn W
authors.initials: MW
authors.lastname: Heymans
authors.forename: Marcel M
authors.initials: MM
authors.lastname: Levi
authors.forename: Albert C
authors.initials: AC
authors.lastname: van Rossum
authors.forename: Hans W M
authors.initials: HW
authors.lastname: Niessen
authors.forename: C Bogdan
authors.initials: CB
authors.lastname: Marcu
authors.forename: Aernout M
authors.initials: AM
authors.lastname: Beek
authors.forename: Niels
authors.initials: N
authors.lastname: van Royen
mesh_terms: D000328:Adult; D000368:Aged; D000818:Animals; D021721:Balloon Occlusion; D009202:Cardiomyopathies / Q000473:pathology*; D003287:Contrast Media; D054059:Coronary Occlusion / Q000473:pathology*; D003328:Coronary Thrombosis / Q000473:pathology; D004195:Disease Models, Animal; D005260:Female; D006470:Hemorrhage / Q000473:pathology*; D006801:Humans; D018810:Magnetic Resonance Angiography; D019028:Magnetic Resonance Imaging, Cine; D008297:Male; D008536:Meglumine; D055806:Microvessels / Q000473:pathology; D008875:Middle Aged; D009203:Myocardial Infarction / Q000473:pathology* / Q000628:therapy; D009204:Myocardial Revascularization / Q000009:adverse effects; D009336:Necrosis / Q000473:pathology; D009942:Organometallic Compounds; D062645:Percutaneous Coronary Intervention; D034421:Sus scrofa
chemical_list: D003287:Contrast Media; D009942:Organometallic Compounds; D008536:Meglumine; C072417:gadoterate meglumine
keywords: Cardiovascular magnetic resonance imaging; Histopathology; Intramyocardial haemorrhage; Microvascular obstruction; Reperfusion injury