Diagnostic performance of noninvasive fractional flow reserve derived from coronary computed tomography angiography in suspected coronary artery disease: the NXT trial (Analysis of Coronary Blood Flow Using CT Angiography: Next Steps).
OBJECTIVE
The goal of this study was to determine the diagnostic performance of noninvasive fractional flow reserve (FFR) derived from standard acquired coronary computed tomography angiography (CTA) datasets (FFR(CT)) for the diagnosis of myocardial ischemia in patients with suspected stable coronary artery disease (CAD).


BACKGROUND
FFR measured during invasive coronary angiography (ICA) is the gold standard for lesion-specific coronary revascularization decisions in patients with stable CAD. The potential for FFR(CT) to noninvasively identify ischemia in patients with suspected CAD has not been sufficiently investigated.


METHODS
This prospective multicenter trial included 254 patients scheduled to undergo clinically indicated ICA for suspected CAD. Coronary CTA was performed before ICA. Evaluation of stenosis (>50% lumen reduction) in coronary CTA was performed by local investigators and in ICA by an independent core laboratory. FFR(CT) was calculated and interpreted in a blinded fashion by an independent core laboratory. Results were compared with invasively measured FFR, with ischemia defined as FFR(CT) or FFR ≤0.80.


RESULTS
The area under the receiver-operating characteristic curve for FFR(CT) was 0.90 (95% confidence interval [CI]: 0.87 to 0.94) versus 0.81 (95% CI: 0.76 to 0.87) for coronary CTA (p = 0.0008). Per-patient sensitivity and specificity (95% CI) to identify myocardial ischemia were 86% (95% CI: 77% to 92%) and 79% (95% CI: 72% to 84%) for FFR(CT) versus 94% (86 to 97) and 34% (95% CI: 27% to 41%) for coronary CTA, and 64% (95% CI: 53% to 74%) and 83% (95% CI: 77% to 88%) for ICA, respectively. In patients (n = 235) with intermediate stenosis (95% CI: 30% to 70%), the diagnostic accuracy of FFR(CT) remained high.


CONCLUSIONS
FFR(CT) provides high diagnostic accuracy and discrimination for the diagnosis of hemodynamically significant CAD with invasive FFR as the reference standard. When compared with anatomic testing by using coronary CTA, FFR(CT) led to a marked increase in specificity. (HeartFlowNXT-HeartFlow Analysis of Coronary Blood Flow Using Coronary CT Angiography [HFNXT]; NCT01757678).
Department of Cardiology, Aarhus University Hospital Skejby, Aarhus, Denmark. Electronic address: bnorgaard@dadlnet.dk.
Bjarne L
BL
Nørgaard
Department of Radiology, St. Paul's Hospital, University of British Columbia, Vancouver, British Columbia, Canada.
Jonathon
J
Leipsic
Department of Cardiology, Aarhus University Hospital Skejby, Aarhus, Denmark.
Sara
S
Gaur
MonashHeart, Monash Medical Center and Monash University, Victoria, Australia.
Sujith
S
Seneviratne
MonashHeart, Monash Medical Center and Monash University, Victoria, Australia.
Brian S
BS
Ko
Department of Cardiology, Okayama University Hospital, Okayama, Japan.
Hiroshi
H
Ito
Department of Cardiology, Aarhus University Hospital Skejby, Aarhus, Denmark.
Jesper M
JM
Jensen
Division of Cardiovascular Medicine, Brigham and Women's Hospital, Boston, Massachusetts.
Laura
L
Mauri
Cardiovascular Center Aalst, OLV-Clinic, Aalst, Belgium.
Bernard
B
De Bruyne
Department of Cardiology, Harrington Heart and Vascular Institute, University Hospitals, Cleveland, Ohio.
Hiram
H
Bezerra
Department of Cardiology, Okayama University Hospital, Okayama, Japan.
Kazuhiro
K
Osawa
Department of Cardiology, Erlangen University Hospital, Erlangen, Germany.
Mohamed
M
Marwan
Department of Cardiology and Angiology, Elisabeth-Krankenhaus Essen, Essen, Germany.
Christoph
C
Naber
Latvian Centre of Cardiology, Pauls Stradins Clinical University Hospital, Riga, Latvia.
Andrejs
A
Erglis
Heart Institute, University of Ulsan College of Medicine, Asan Medical Center, Seoul, South Korea.
Seung-Jung
SJ
Park
Department of Cardiology, Aarhus University Hospital Skejby, Aarhus, Denmark.
Evald H
EH
Christiansen
Department of Cardiology, Aarhus University Hospital Skejby, Aarhus, Denmark.
Anne
A
Kaltoft
Department of Cardiology, Aarhus University Hospital Skejby, Aarhus, Denmark.
Jens F
JF
Lassen
Department of Cardiology, Aarhus University Hospital Skejby, Aarhus, Denmark.
Hans Erik
HE
Bøtker
Department of Cardiology, Erlangen University Hospital, Erlangen, Germany.
Stephan
S
Achenbach
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D003198:Computer Simulation; D017023:Coronary Angiography; D003324:Coronary Artery Disease / Q000000981:diagnostic imaging* / Q000503:physiopathology; D023921:Coronary Stenosis / Q000000981:diagnostic imaging / Q000503:physiopathology; D005260:Female; D053805:Fractional Flow Reserve, Myocardial / Q000502:physiology*; D006801:Humans; D021621:Imaging, Three-Dimensional; D008297:Male; D008833:Microcirculation / Q000502:physiology; D008875:Middle Aged; D061330:Multidetector Computed Tomography; D017202:Myocardial Ischemia / Q000175:diagnosis* / Q000503:physiopathology; D011237:Predictive Value of Tests; D011446:Prospective Studies; D012372:ROC Curve; D012680:Sensitivity and Specificity
computational fluid dynamics; coronary CT angiography; fractional flow reserve; invasive coronary angiography