Bifurcation lesions: Functional assessment by fractional flow reserve vs. anatomical assessment using conventional and dedicated bifurcation quantitative coronary angiogram

Background: The purpose of this study was to compare the performance of both conventional quantitative coronary angiography (QCA) and the dedicated three branch QCA model for bifurcations in the prediction of a functionally significant lesion according to fractional flow reserve (FFR) in patients with bifurcation lesions. Methods: Twenty patients with bifurcation lesions underwent coronary angiography together with a functional evaluation of both the main branch and side-branch using FFR. QCA was performed off-line with both conventional QCA software (CAASII, Pie Medical Imaging, Maastricht, The Netherlands) and three branch QCA software (CAAS5, Pie Medical Imaging, Maastricht, The Netherlands). A stenosis was considered hemodynamically significant when the FFR value was ≤0.80 and anatomically significant when the diameter stenosis was >50%. The QCA and FFR data were correlated by means of the Pearson correlation. Results: Eighteen bifurcation lesions were suitable for the QCA analysis. In the main vessel, a significant inverse correlation with FFR was seen with both conventional QCA (Pearson r = 0.52 for the MV, P = 0.02), and the three branch QCA model (Pearson r = 0.67 for the MV, P = 0.002). Conversely, in the side-branch, the correlation between QCA and FFR was only significant with the three branch QCA model (Pearson r = 0.57, P = 0.02 for the SB). Conclusions: In bifurcation lesions the correlation between the anatomic severity of a coronary stenosis and its functional significance appears to be somewhat higher when QCA is performed using the three branch model. This is most notable for side-branch stenoses which can be overestimated when using conventional QCA.