Prognosis of CT-derived Fractional Flow Reserve in the Prediction of Clinical Outcomes

Charis G McNabney; Stephanie L Sellers; Ryan J A Wilson; Shmuel Hart; Samuel A Rosenblatt; Darra T Murphy; Philipp Blanke; Amir A Ahmadi; Jaydeep Halankar; Adrian Attinger-Toller; Marcelo Godoy Zamorano; Janice Wong Li Yu; Bjarne L Nørgaard; Jonathon A Leipsic; Jonathan R Weir-McCall

doi:10.1148/ryct.2019190021

Prognosis of CT-derived Fractional Flow Reserve in the Prediction of Clinical Outcomes

Radiol Cardiothorac Imaging. 2019 Jun 27;1(2):e190021. doi: 10.1148/ryct.2019190021. eCollection 2019 Jun.

Authors

Affiliation

¹ Department of Radiology (C.G.M., S.L.S., S.H., S.A.R., D.T.M., P.B., J.H., M.G.Z., J.A.L., J.R.W.M.), Centre for Heart Lung Innovation (S.L.S., J.W.L.Y., J.A.L.), and Department of Cardiology (A.A.A., A.A.T., J.A.L.), St Paul's Hospital and University of British Columbia, 1081 Burrard St., Vancouver, British Columbia, Canada, V6Z 1Y6; Department of Radiology, Vancouver General Hospital and University of British Columbia, Vancouver, Canada (R.J.A.W.); Department of Cardiology, Aarhus University Hospital Skejby, Aarhus, Denmark (B.L.N.); School of Medicine, University of Cambridge, Cambridge, England (J.R.W.M.).

Abstract

Purpose: To examine the prognostic implication of fractional flow reserve (FFR) derived from coronary CT (FFR_CT) in routine clinical practice.

Materials and methods: Patients referred for FFR_CT analysis at a single center between October 2015 and June 2017 were retrospectively included and followed up for rates of invasive angiography and clinical events. Two hundred seven patients underwent successful FFR_CT analysis with seven lost to follow-up, leaving 200 (mean age ± standard deviation, 62.4 years ± 10.0; 49 [24.5%] women) patients for analysis. At coronary CT angiography, patients were categorized as having significant stenosis (SS) in the presence of a diameter stenosis greater than or equal to 50% (hereafter, SS positive) and flow limitation in the presence of a postlesion (that is, FFR_CT measured 2 cm to the distal aspect of the lesion) FFR_CT less than 0.80 (hereafter, FFR_CT positive). Vessel-oriented clinical events (VOCEs) were defined as vessel-related late revascularization (>90 days), myocardial infarction, and cardiac mortality.

Results: At CT angiography, 130 (65%) studies were SS positive and 63 (31.5%) were FFR_CT positive. At median follow-up of 477 days (range, 252-859 days), there were 26 VOCE end points in 22 patients: 22 revascularizations and four nonfatal myocardial infarctions. VOCE end points occurred in zero of 58 (0%) of SS-negative and FFR_CT negative patients, in eight of 79 (10.1%) of SS-positive and FFR_CT-negative patients, in zero of 12 (0%) of SS-negative and FFR_CT-positive patients, and in 18 of 51 (35.3%) of SS-positive and FFR_CT-positive patients (log-rank χ² = 30.1; P < .001). At multivariable Cox regression, both FFR_CT (hazard ratio per 0.1 decrease, 1.54 [95% confidence interval: 1.1, 2.2] P = .013) and stenosis (hazard ratio per unit increase, 2.16 [95% confidence interval: 1.25, 3.72] P = .006) were independently associated with VOCE.

Conclusion: Stenosis and FFR_CT are independent predictors of intermediate-term outcomes. In the absence of a stenosis greater than 50%, a positive FFR_CT result is not associated with an increased intermediate risk.© RSNA, 2019Supplemental material is available for this article.See also commentary by Fairbairn and Bull in this issue.

2019 by the Radiological Society of North America, Inc.