title: Diagnostic accuracy of fractional flow reserve from anatomic CT angiography.
abstract: BACKGROUND
  Coronary computed tomographic (CT) angiography is a noninvasive anatomic test for diagnosis of coronary stenosis that does not determine whether a stenosis causes ischemia. In contrast, fractional flow reserve (FFR) is a physiologic measure of coronary stenosis expressing the amount of coronary flow still attainable despite the presence of a stenosis, but it requires an invasive procedure. Noninvasive FFR computed from CT (FFR(CT)) is a novel method for determining the physiologic significance of coronary artery disease (CAD), but its ability to identify ischemia has not been adequately examined to date.
  
  
  OBJECTIVE
  To assess the diagnostic performance of FFR(CT) plus CT for diagnosis of hemodynamically significant coronary stenosis.
  
  
  METHODS
  Multicenter diagnostic performance study involving 252 stable patients with suspected or known CAD from 17 centers in 5 countries who underwent CT, invasive coronary angiography (ICA), FFR, and FFR(CT) between October 2010 and October 2011. Computed tomography, ICA, FFR, and FFR(CT) were interpreted in blinded fashion by independent core laboratories. Accuracy of FFR(CT) plus CT for diagnosis of ischemia was compared with an invasive FFR reference standard. Ischemia was defined by an FFR or FFR(CT) of 0.80 or less, while anatomically obstructive CAD was defined by a stenosis of 50% or larger on CT and ICA.
  
  
  METHODS
  The primary study outcome assessed whether FFR(CT) plus CT could improve the per-patient diagnostic accuracy such that the lower boundary of the 1-sided 95% confidence interval of this estimate exceeded 70%.
  
  
  RESULTS
  Among study participants, 137 (54.4%) had an abnormal FFR determined by ICA. On a per-patient basis, diagnostic accuracy, sensitivity, specificity, positive predictive value, and negative predictive value of FFR(CT) plus CT were 73% (95% CI, 67%-78%), 90% (95% CI, 84%-95%), 54% (95% CI, 46%-83%), 67% (95% CI, 60%-74%), and 84% (95% CI, 74%-90%), respectively. Compared with obstructive CAD diagnosed by CT alone (area under the receiver operating characteristic curve [AUC], 0.68; 95% CI, 0.62-0.74), FFR(CT) was associated with improved discrimination (AUC, 0.81; 95% CI, 0.75-0.86; P < .001).
  
  
  CONCLUSIONS
  Although the study did not achieve its prespecified primary outcome goal for the level of per-patient diagnostic accuracy, use of noninvasive FFR(CT) plus CT among stable patients with suspected or known CAD was associated with improved diagnostic accuracy and discrimination vs CT alone for the diagnosis of hemodynamically significant CAD when FFR determined at the time of ICA was the reference standard.
authors.affiliation: Cedars-Sinai Heart Institute and David Geffen University of California, Los Angeles, School of Medicine, Los Angeles, CA 90048, USA. James.Min@cshs.org
authors.forename: James K
authors.initials: JK
authors.lastname: Min
authors.forename: Jonathon
authors.initials: J
authors.lastname: Leipsic
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Pencina
authors.forename: Daniel S
authors.initials: DS
authors.lastname: Berman
authors.forename: Bon-Kwon
authors.initials: BK
authors.lastname: Koo
authors.forename: Carlos
authors.initials: C
authors.lastname: van Mieghem
authors.forename: Andrejs
authors.initials: A
authors.lastname: Erglis
authors.forename: Fay Y
authors.initials: FY
authors.lastname: Lin
authors.forename: Allison M
authors.initials: AM
authors.lastname: Dunning
authors.forename: Patricia
authors.initials: P
authors.lastname: Apruzzese
authors.forename: Matthew J
authors.initials: MJ
authors.lastname: Budoff
authors.forename: Jason H
authors.initials: JH
authors.lastname: Cole
authors.forename: Farouc A
authors.initials: FA
authors.lastname: Jaffer
authors.forename: Martin B
authors.initials: MB
authors.lastname: Leon
authors.forename: Jennifer
authors.initials: J
authors.lastname: Malpeso
authors.forename: G B John
authors.initials: GB
authors.lastname: Mancini
authors.forename: Seung-Jung
authors.initials: SJ
authors.lastname: Park
authors.forename: Robert S
authors.initials: RS
authors.lastname: Schwartz
authors.forename: Leslee J
authors.initials: LJ
authors.lastname: Shaw
authors.forename: Laura
authors.initials: L
authors.lastname: Mauri
mesh_terms: D000368:Aged; D017023:Coronary Angiography; D003326:Coronary Circulation; D023921:Coronary Stenosis / Q000000981:diagnostic imaging* / Q000503:physiopathology*; D005260:Female; D053805:Fractional Flow Reserve, Myocardial; D006801:Humans; D008297:Male; D008875:Middle Aged; D017202:Myocardial Ischemia / Q000000981:diagnostic imaging* / Q000503:physiopathology; D012016:Reference Values; D012680:Sensitivity and Specificity; D014057:Tomography, X-Ray Computed