Correlation between coronary computed tomographic angiography and fractional flow reserve ☆ Thomas Skaarup Kristensen a, ⁎, Thomas Engstrøm b , Henning Kelbæk b , Peter von der Recke a , Michael Bachmann Nielsen a , Klaus Fuglsang Kofoed b a Department of Radiology, Rigshospitalet, University of Copenhagen, Blegdamsvej 9, 2100 Copenhagen, Denmark b Cardiac Catheterization Laboratory, Department of Cardiology, Rigshospitalet, University of Copenhagen, Blegdamsvej 9, 2100 Copenhagen, Denmark abstract article info Article history: Received 19 January 2009 Received in revised form 31 March 2009 Accepted 11 April 2009 Available online 9 May 2009 Keywords: Coronary artery disease Computed tomography Fractional flow reserve Background: Coronary CT angiography (CCTA) has become an important modality to evaluate the presence of coronary artery disease. Coronary artery stenosis of intermediate severity remains a therapeutic dilemma. Measurement of fractional flow reserve (FFR) during coronary angiography is the most established technique to determine the hemodynamic severity of a coronary artery lesion. The aim of this study was to compare CCTA with FFR. Methods: In 56 coronary artery stenoses (42 patients) we performed CCTA, quantitative coronary angiography and FFR. CCTA measurements included diameter stenosis (DS, %), area stenosis (AS, %), minimal lumen diameter (MLD, mm), minimal lumen area (MLA, mm 2 ), lesion length (LL, mm), plaque volume (mm 3 ) and burden (%). Results: FFR averaged 0.81±0.14, and 10 lesions had an abnormal FFR (b 0.75). We found significant correlations between FFR and DS (r =-0.67, p b 0.001), AS (r =-0.68, p b 0.001), MLD (r = 0.58, p b 0.001), MLA (r = 0.53, p b 0.001), LL (r =-0.36, p = 0.02), plaque volume (r =-0.36, p = 0.02) and plaque burden (r =-0.59, p b 0.001). By multivariate regression analysis AS and LL were the strongest determinants of an abnormal FFR. The optimal cut-off value for AS was N 73% (sensitivity 90%, specificity 80%, negative predictive value 97%, and positive predictive value 50%) and for LL N 10 mm (sensitivity 60% and specificity 49%). Conclusion: This study demonstrates that quantitative CCTA is correlated to FFR. Using our CCTA criteria of abnormality, significant coronary artery stenoses can be ruled out with a high negative predictive value. © 2009 Elsevier Ireland Ltd. All rights reserved. 1. Introduction Invasive coronary angiography (CAG) is the established technique for assessment of coronary arteries in patients with suspected or known coronary artery disease (CAD). Recent technological advances in multi-detector row computed tomography (MDCT) have improved image quality considerably, and coronary CT angiography (CCTA) has become an integral part of the diagnostic work-up in patients suspected for CAD [1–5]. So far, visual assessment of CCTA has proved to be a reliable tool for ruling out significant CAD in patients with stable angina or atypical chest pain and low to intermediate pretest likelihood for CAD. However, the specificity of the method has been limited by a relatively large proportion of false positives in patients with severe calcifica- tions, and grading of stenoses has so far demonstrated large limits of agreement in comparison with quantitative coronary angiography (QCA) [6–9]. New semiautomatic tools for quantitative measurements of CT images have now been introduced allowing more detailed and reliable grading of coronary artery stenoses [10]. Invasive CAG provides useful anatomical information about the degree of luminal narrowing, but the functional significance is not assessed directly, and in patients with intermediate coronary stenosis, clinical decision-making often relies on supplemental functional tests [11,12]. The fractional flow reserve (FFR) is a measurement of the functional severity of a stenosis based on the pressure changes over a lesion during maximal coronary hyperemia. FFR has been shown to correlate well with non-invasive modalities such as perfusion scintigraphy, stress echocardiography and bicycle exercise [13–15], and prognostic studies support that deferral from revascularization in patients with an FFR N 0.75 results in good clinical outcomes [16–18]. Furthermore, measurements of FFR can be performed in combination with invasive CAG, thus combining morphologic and functional information in one procedure enabling ad hoc percutaneous revascularization. Studies using intravascular ultrasound (IVUS) have suggested that cross-sectional measurements of coronary stenoses of intermediate severity are correlated with FFR [19–22]. CCTA also permits assessment International Journal of Cardiology 144 (2010) 200–205 ☆ This study was supported by the John and Birthe Meyer Foundation, the Aase and Ejner Danielsens Foundation and Ge Healthcare. ⁎ Corresponding author. E-mail address: tskaarup@yahoo.com (T.S. Kristensen). 0167-5273/$ – see front matter © 2009 Elsevier Ireland Ltd. All rights reserved. doi:10.1016/j.ijcard.2009.04.024 Contents lists available at ScienceDirect International Journal of Cardiology journal homepage: www.elsevier.com/locate/ijcard