title: A virtual histology intravascular ultrasound analysis of coronary chronic total occlusions.
abstract: OBJECTIVE
  We used virtual histology intravascular ultrasound (VH-IVUS) to investigate plaque composition of chronic total occlusions (CTO).
  
  
  BACKGROUND
  There are limited data on the composition of CTOs, especially in vivo.
  
  
  METHODS
  VH-IVUS was performed in 50 CTO lesions (49 patients) after guidewire crossing or pre-dilation using a 1.5-2 mm balloon. Plaque composition in the proximal reference, distal reference, and CTO segment (subsequently divided into proximal, middle, and distal subsegments) was analyzed and reported as median and interquartile range. VH-IVUS phenotype was also assessed. The definition of a fibroatheroma was >10% confluent necrotic core (NC) in more than three consecutive frames.
  
  
  RESULTS
  Overall, the maximum NC within the CTO [35.5% (28.7, 44.3%)] was similar to the proximal reference [35.6% (24.1, 42.1%)] and greater than the distal reference [31.5% (22.6, 35.2%), P < 0.01]. There was no difference in maximum NC observed among proximal [31.4% (25.2, 10.4%)], middle [31.0% (23.3, 38.3%)], and distal CTO subsegments [30.4% (22.0, 39.5%)]. Overall, 42/50 CTOs contained a VH-fibroathroma; and 8/50 did not. CTOs containing a VH-fibroatheroma had more NC and dense calcium while CTOs not containing a fibroatheroma had more fibrotic and fibrofatty plaque. Importantly, 60.5% of VH-fibroatheroma-containing CTOs had a thin-cap fibroatheroma (NC abutted to the lumen) in the proximal reference.
  
  
  CONCLUSIONS
  Using VH-IVUS, CTO morphology can be divided into two patterns: (1) CTO with VH-fibroatheroma or (2) CTO without VH-fibroatheroma. This suggests two mechanisms of CTO formation-the majority evolving from acute coronary syndrome and thrombosis and the minority from atherosclerosis progression.
authors.affiliation: Columbia University Medical Center and the Cardiovascular Research Foundation, New York, NY, USA.
authors.forename: Jun
authors.initials: J
authors.lastname: Guo
authors.forename: Akiko
authors.initials: A
authors.lastname: Maehara
authors.forename: Gary S
authors.initials: GS
authors.lastname: Mintz
authors.forename: Kazuhiro
authors.initials: K
authors.lastname: Ashida
authors.forename: Jun
authors.initials: J
authors.lastname: Pu
authors.forename: Yunpeng
authors.initials: Y
authors.lastname: Shang
authors.forename: Martin B
authors.initials: MB
authors.lastname: Leon
authors.forename: Gregg W
authors.initials: GW
authors.lastname: Stone
authors.forename: Jeffrey W
authors.initials: JW
authors.lastname: Moses
authors.forename: Masahiko
authors.initials: M
authors.lastname: Ochiai
mesh_terms: D000368:Aged; D002908:Chronic Disease; D054059:Coronary Occlusion / Q000000981:diagnostic imaging* / Q000209:etiology; D003331:Coronary Vessels / Q000000981:diagnostic imaging*; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods*; D008297:Male; D008875:Middle Aged; D058226:Plaque, Atherosclerotic / Q000150:complications / Q000000981:diagnostic imaging*; D015203:Reproducibility of Results; D012189:Retrospective Studies; D012720:Severity of Illness Index; D018084:Ultrasonography, Interventional / Q000379:methods*; D014584:User-Computer Interface