title: Influence of Coronary Calcification on the Diagnostic Performance of CT Angiography Derived FFR in Coronary Artery Disease: A Substudy of the NXT Trial.
abstract: OBJECTIVE
  The goal of this study was to examine the diagnostic performance of noninvasive fractional flow reserve (FFR) derived from coronary computed tomography angiography (CTA) (FFRCT) in relation to coronary calcification severity.
  
  
  BACKGROUND
  FFRCT has shown promising results in identifying lesion-specific ischemia. The extent to which the severity of coronary calcification affects the diagnostic performance of FFRCT is not known.
  
  
  METHODS
  Coronary calcification was assessed by using the Agatston score (AS) in 214 patients suspected of having coronary artery disease who underwent coronary CTA, FFRCT, and FFR (FFR examination was performed in 333 vessels). The diagnostic performance of FFRCT (≤0.80) in identifying vessel-specific ischemia (FFR ≤0.80) was investigated across AS quartiles (Q1 to Q4) and for discrimination of ischemia in patients and vessels with a low-mid AS (Q1 to Q3) versus a high AS (Q4). Coronary CTA stenosis was defined as lumen reduction >50%.
  
  
  RESULTS
  Mean ± SD per-patient and per-vessel AS were 302 ± 468 (range 0 to 3,599) and 95 ± 172 (range 0 to 1,703), respectively. There was no statistical difference in diagnostic accuracy, sensitivity, or specificity of FFRCT across AS quartiles. Discrimination of ischemia by FFRCT was high in patients with a high AS (416 to 3,599) and a low-mid AS (0 to 415), with no difference in area under the receiver-operating characteristic curve (AUC) (0.86 [95% confidence interval (CI): 0.76 to 0.96] vs. 0.92 [95% CI: 0.88 to 0.96]) (p = 0.45). Similarly, discrimination of ischemia by FFRCT was high in vessels with a high AS (121 to 1,703) and a low-mid AS (0 to 120) (AUC: 0.91 [95% CI: 0.85 to 0.97] vs. 0.95 [95% CI: 0.91 to 0.98]; p = 0.65). Diagnostic accuracy and specificity of FFRCT were significantly higher than for stenosis assessment in each AS quartile at the per-patient (p < 0.001) and per-vessel (p < 0.05) level with similar sensitivity. In vessels with a high AS, FFRCT exhibited improved discrimination of ischemia compared with coronary CTA alone (AUC: 0.91 vs. 0.71; p = 0.004), whereas on a per-patient level, the difference did not reach statistical significance (AUC: 0.86 vs. 0.72; p = 0.09).
  
  
  CONCLUSIONS
  FFRCT provided high and superior diagnostic performance compared with coronary CTA interpretation alone in patients and vessels with a high AS.
authors: Department of Cardiology, Aarhus University Hospital Skejby, Aarhus, Denmark. Electronic address: bnorgaard@dadlnet.dk.
authors: Bjarne L
authors: BL
authors: Nørgaard
authors: Department of Cardiology, Aarhus University Hospital Skejby, Aarhus, Denmark.
authors: Sara
authors: S
authors: Gaur
authors: Department of Radiology, St. Paul's Hospital, University of British Columbia, Vancouver, British Columbia, Canada.
authors: Jonathon
authors: J
authors: Leipsic
authors: Department of Cardiology, Okayama University Hospital, Okayama, Japan.
authors: Hiroshi
authors: H
authors: Ito
authors: Department of Cardiology, Okayama University Hospital, Okayama, Japan.
authors: Toru
authors: T
authors: Miyoshi
authors: Heart Institute, University of Ulsan College of Medicine, Asan Medical Center, Seoul, South Korea.
authors: Seung-Jung
authors: SJ
authors: Park
authors: Diagnostic Institute of Radiology, Paul Stradins Clinical University Hospital, Riga, Latvia.
authors: Ligita
authors: L
authors: Zvaigzne
authors: Department of Radiology, Golden Jubilee Hospital, Glasgow, Scotland.
authors: Nikolaos
authors: N
authors: Tzemos
authors: Department of Cardiology, Aarhus University Hospital Skejby, Aarhus, Denmark.
authors: Jesper M
authors: JM
authors: Jensen
authors: Department of Cardiology, Aarhus University Hospital Skejby, Aarhus, Denmark.
authors: Nicolaj
authors: N
authors: Hansson
authors: MonashHeart, Monash Medical Center and Monash University, Victoria, Australia.
authors: Brian
authors: B
authors: Ko
authors: Department of Cardiology, Harrington Heart and Vascular Institute, University Hospitals, Cleveland, Ohio.
authors: Hiram
authors: H
authors: Bezerra
authors: Department of Cardiology, Aarhus University Hospital Skejby, Aarhus, Denmark.
authors: Evald H
authors: EH
authors: Christiansen
authors: Department of Cardiology, Aarhus University Hospital Skejby, Aarhus, Denmark.
authors: Anne
authors: A
authors: Kaltoft
authors: Department of Cardiology, Aarhus University Hospital Skejby, Aarhus, Denmark.
authors: Jens F
authors: JF
authors: Lassen
authors: Department of Cardiology, Aarhus University Hospital Skejby, Aarhus, Denmark.
authors: Hans Erik
authors: HE
authors: Bøtker
authors: Department of Cardiology, Erlangen University Hospital, Erlangen, Germany.
authors: Stephan
authors: S
authors: Achenbach
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D019540:Area Under Curve; D017023:Coronary Angiography / Q000379:methods*; D003324:Coronary Artery Disease / Q000000981:diagnostic imaging* / Q000503:physiopathology; D023921:Coronary Stenosis / Q000000981:diagnostic imaging* / Q000503:physiopathology; D003331:Coronary Vessels / Q000000981:diagnostic imaging* / Q000503:physiopathology; D005260:Female; D053805:Fractional Flow Reserve, Myocardial; D006801:Humans; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D011446:Prospective Studies; D012372:ROC Curve; D015203:Reproducibility of Results; D012720:Severity of Illness Index; D014057:Tomography, X-Ray Computed; D061205:Vascular Calcification / Q000000981:diagnostic imaging* / Q000503:physiopathology
keywords: computed tomography angiography; coronary angiography; coronary artery disease; coronary calcification; fractional flow reserve