title: Coronary plaque quantification and fractional flow reserve by coronary computed tomography angiography identify ischaemia-causing lesions.
abstract: OBJECTIVE
  Coronary plaque characteristics are associated with ischaemia. Differences in plaque volumes and composition may explain the discordance between coronary stenosis severity and ischaemia. We evaluated the association between coronary stenosis severity, plaque characteristics, coronary computed tomography angiography (CTA)-derived fractional flow reserve (FFRCT), and lesion-specific ischaemia identified by FFR in a substudy of the NXT trial (Analysis of Coronary Blood Flow Using CT Angiography: Next Steps).
  
  
  RESULTS
  Coronary CTA stenosis, plaque volumes, FFRCT, and FFR were assessed in 484 vessels from 254 patients. Stenosis >50% was considered obstructive. Plaque volumes (non-calcified plaque [NCP], low-density NCP [LD-NCP], and calcified plaque [CP]) were quantified using semi-automated software. Optimal thresholds of quantitative plaque variables were defined by area under the receiver-operating characteristics curve (AUC) analysis. Ischaemia was defined by FFR or FFRCT ≤0.80. Plaque volumes were inversely related to FFR irrespective of stenosis severity. Relative risk (95% confidence interval) for prediction of ischaemia for stenosis >50%, NCP ≥185 mm(3), LD-NCP ≥30 mm(3), CP ≥9 mm(3), and FFRCT ≤0.80 were 5.0 (3.0-8.3), 3.7 (2.4-5.6), 4.6 (2.9-7.4), 1.4 (1.0-2.0), and 13.6 (8.4-21.9), respectively. Low-density NCP predicted ischaemia independent of other plaque characteristics. Low-density NCP and FFRCT yielded diagnostic improvement over stenosis assessment with AUCs increasing from 0.71 by stenosis >50% to 0.79 and 0.90 when adding LD-NCP ≥30 mm(3) and LD-NCP ≥30 mm(3) + FFRCT ≤0.80, respectively.
  
  
  CONCLUSIONS
  Stenosis severity, plaque characteristics, and FFRCT predict lesion-specific ischaemia. Plaque assessment and FFRCT provide improved discrimination of ischaemia compared with stenosis assessment alone.
authors.affiliation: Department of Cardiology, Aarhus University Hospital, Palle Juul-Jensens Boulevard 99, 8200 Aarhus N, Denmark saga@clin.au.dk.
authors.forename: Sara
authors.initials: S
authors.lastname: Gaur
authors.affiliation: Department of Cardiology, Aarhus University Hospital, Palle Juul-Jensens Boulevard 99, 8200 Aarhus N, Denmark.
authors.forename: Kristian Altern
authors.initials: KA
authors.lastname: Øvrehus
authors.affiliation: Department of Biomedical Sciences, Cedars-Sinai Medical Center, Los Angeles, CA, USA.
authors.forename: Damini
authors.initials: D
authors.lastname: Dey
authors.affiliation: Department of Radiology, Division of Cardiology, St. Paul's Hospital, Vancouver, BC, Canada.
authors.forename: Jonathon
authors.initials: J
authors.lastname: Leipsic
authors.affiliation: Department of Cardiology, Aarhus University Hospital, Palle Juul-Jensens Boulevard 99, 8200 Aarhus N, Denmark.
authors.forename: Hans Erik
authors.initials: HE
authors.lastname: Bøtker
authors.affiliation: Department of Cardiology, Aarhus University Hospital, Palle Juul-Jensens Boulevard 99, 8200 Aarhus N, Denmark.
authors.forename: Jesper Møller
authors.initials: JM
authors.lastname: Jensen
authors.affiliation: Icahn School of Medicine at Mount Sinai, New York, NY, USA.
authors.forename: Jagat
authors.initials: J
authors.lastname: Narula
authors.affiliation: Department of Radiology, Division of Cardiology, St. Paul's Hospital, Vancouver, BC, Canada.
authors.forename: Amir
authors.initials: A
authors.lastname: Ahmadi
authors.affiliation: Department of Cardiology, University of Erlangen, Erlangen, Germany.
authors.forename: Stephan
authors.initials: S
authors.lastname: Achenbach
authors.affiliation: Monash Cardiovascular Research Centre, Monash University and Monash Heart, Clayton, Australia.
authors.forename: Brian S
authors.initials: BS
authors.lastname: Ko
authors.affiliation: Department of Cardiology, Aarhus University Hospital, Palle Juul-Jensens Boulevard 99, 8200 Aarhus N, Denmark.
authors.forename: Evald Høj
authors.initials: EH
authors.lastname: Christiansen
authors.affiliation: Department of Cardiology, Aarhus University Hospital, Palle Juul-Jensens Boulevard 99, 8200 Aarhus N, Denmark.
authors.forename: Anne Kjer
authors.initials: AK
authors.lastname: Kaltoft
authors.affiliation: Department of Imaging, Cedars-Sinai Medical Center, Los Angeles, CA, USA.
authors.forename: Daniel S
authors.initials: DS
authors.lastname: Berman
authors.affiliation: Department of Cardiology, Harrington Heart and Vascular Institute, University Hospitals of Cleveland, Cleveland, OH, USA.
authors.forename: Hiram
authors.initials: H
authors.lastname: Bezerra
authors.affiliation: Department of Cardiology, Aarhus University Hospital, Palle Juul-Jensens Boulevard 99, 8200 Aarhus N, Denmark.
authors.forename: Jens Flensted
authors.initials: JF
authors.lastname: Lassen
authors.affiliation: Department of Cardiology, Aarhus University Hospital, Palle Juul-Jensens Boulevard 99, 8200 Aarhus N, Denmark.
authors.forename: Bjarne Linde
authors.initials: BL
authors.lastname: Nørgaard
mesh_terms: D000072226:Computed Tomography Angiography; D023921:Coronary Stenosis / Q000000981:diagnostic imaging / Q000503:physiopathology; D005260:Female; D053805:Fractional Flow Reserve, Myocardial / Q000502:physiology; D006801:Humans; D008297:Male; D008875:Middle Aged; D017202:Myocardial Ischemia / Q000000981:diagnostic imaging* / Q000503:physiopathology; D058226:Plaque, Atherosclerotic / Q000000981:diagnostic imaging* / Q000503:physiopathology; D020257:Ventricular Remodeling / Q000502:physiology
keywords: Computational fluid dynamics; Computed tomography angiography; Coronary plaque; Fractional flow reserve; Ischaemia