title: Vulnerable plaque features on coronary CT angiography as markers of inducible regional myocardial hypoperfusion from severe coronary artery stenoses.
abstract: OBJECTIVE
  We explored whether the presence of 3 known features of plaque vulnerability on coronary CT angiography (CCTA)--low attenuation plaque content (LAP), positive remodeling (PR), and spotty calcification (SC)--identifies plaques associated with greater inducible myocardial hypoperfusion measured by myocardial perfusion imaging (MPI).
  
  
  METHODS
  We analyzed 49 patients free of cardiac disease who underwent CCTA and MPI within a 6-month period and were found on CCTA to have focal 70-99% stenosis from predominantly non-calcified plaque in the proximal or mid segment of 1 major coronary artery. Presence of LAP (≤ 30 Hounsfield Units), PR (outer wall diameter exceeds proximal reference by ≥ 5%), and SC (≤ 3 mm long and occupies ≤ 90° of cross-sectional artery circumference) was determined. On MPI, reversible hypoperfusion in the myocardial territory corresponding to the diseased artery was quantified both as percentage of total myocardium (RevTPD(ART)) by an automatic algorithm and as summed difference score (SDS(ART)) by two experienced readers. RevTPD(ART)≥ 3% and SDS(ART)≥ 3 defined significant inducible hypoperfusion in the territory of the diseased artery.
  
  
  RESULTS
  Plaques in patients with RevTPD(ART)≥ 3% more frequently exhibited LAP (70% vs. 14%, p < 0.001) and PR (70% vs. 24%, p = 0.001) but not SC (55% vs. 34%, p = 0.154). RevTPD(ART) increased from 1.3 ± 1.2% in arteries with LAP-/PR- plaques to 3.2 ± 4.3% with LAP+/PR- or LAP-/PR+ plaques to 8.3 ± 2.4% with LAP+/PR+ plaques (p < 0.001); SDS(ART) showed a similar increase: 0.3 ± 0.7 to 2.3 ± 2.8 to 6.0 ± 3.8 (p < 0.001). Using the same LAP/PR categorization, there was a marked increase in the frequency of significant hypoperfusion as determined by both RevTPD(ART)≥ 3% (1/19 to 10/21 to 9/9, p < 0.001) and SDS(ART)≥ 3 (1/19 to 8/21 to 8/9, p < 0.001). LAP and PR, but not SC, were strong predictors of RevTPD(ART) and SDS(ART) in regression models adjusting for potential confounders.
  
  
  CONCLUSIONS
  Presence of low attenuation plaque and positive remodeling in severely stenotic plaques on CCTA is strongly predictive of myocardial hypoperfusion and may be useful in assessing the hemodynamic significance of such lesions.
authors.affiliation: Heart Institute and the Departments of Imaging and Medicine, Cedars-Sinai Medical Center, Los Angeles, CA, USA.
authors.forename: Haim
authors.initials: H
authors.lastname: Shmilovich
authors.forename: Victor Y
authors.initials: VY
authors.lastname: Cheng
authors.forename: Balaji K
authors.initials: BK
authors.lastname: Tamarappoo
authors.forename: Damini
authors.initials: D
authors.lastname: Dey
authors.forename: Ryo
authors.initials: R
authors.lastname: Nakazato
authors.forename: Heidi
authors.initials: H
authors.lastname: Gransar
authors.forename: Louise E J
authors.initials: LE
authors.lastname: Thomson
authors.forename: Sean W
authors.initials: SW
authors.lastname: Hayes
authors.forename: John D
authors.initials: JD
authors.lastname: Friedman
authors.forename: Guido
authors.initials: G
authors.lastname: Germano
authors.forename: Piotr J
authors.initials: PJ
authors.lastname: Slomka
authors.forename: Daniel S
authors.initials: DS
authors.lastname: Berman
mesh_terms: D000368:Aged; D000465:Algorithms; D016009:Chi-Square Distribution; D017023:Coronary Angiography / Q000379:methods*; D003326:Coronary Circulation; D023921:Coronary Stenosis / Q000000981:diagnostic imaging* / Q000503:physiopathology; D005260:Female; D006439:Hemodynamics; D006801:Humans; D016014:Linear Models; D016015:Logistic Models; D015141:Los Angeles; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D055414:Myocardial Perfusion Imaging / Q000379:methods*; D016017:Odds Ratio; D058226:Plaque, Atherosclerotic / Q000000981:diagnostic imaging* / Q000503:physiopathology; D049268:Positron-Emission Tomography; D011237:Predictive Value of Tests; D011379:Prognosis; D011857:Radiographic Image Interpretation, Computer-Assisted; D012720:Severity of Illness Index; D015899:Tomography, Emission-Computed, Single-Photon; D014057:Tomography, X-Ray Computed; D061205:Vascular Calcification / Q000000981:diagnostic imaging / Q000503:physiopathology