Interpreting results of coronary computed tomography angiography-derived fractional flow reserve in clinical practice.
J Cardiovasc Comput Tomogr. 2017 Sep - Oct;11(5):383-388. doi: 10.1016/j.jcct.2017.06.002. Epub 2017 Jun 23. Rabbat MG1, Berman DS2, Kern M3, Raff G4, Chinnaiyan K4, Koweek L5, Shaw LJ6, Blanke P7, Scherer M8, Jensen JM9, Lesser J10, Nørgaard BL9, Pontone G11, De Bruyne B12, Bax JJ13, Leipsic J7.
The application of computational fluid dynamics to coronary computed tomography angiography allows Fractional Flow Reserve (FFR) to be calculated non-invasively (FFRCT), enabling computation of FFR from coronary computed tomography angiography acquired at rest both for individual lesions as well as along the entire course of a coronary artery. FFRCT, validated in a number of accuracy studies and a large clinical utility trial, is beginning to penetrate clinical practice. Importantly, while accuracy trials compared FFRCT to invasively measured FFR at a single point in the coronary tree, clinical reports of FFRCT provide information regarding a patient's entire coronary vasculature. Specifically, in distal coronary segments, calculated FFRCT values may be low and below 0.80 even in the absence of localized stenoses within the course of the artery. As a result, the reporting physician needs to understand how to interpret the findings in a clinically useful and thoughtful fashion. This review provides a brief overview of the background of both invasively measured and computationally derived FFR, explains changes in FFR along the course of normal coronary arteries and those affected by coronary atherosclerosis, and outlines the relevance of measurement location when interpreting and reporting FFR and FFRCT results.