Quantitative Coronary Analysis and QFR Analysis and Virtual Stenting

All angiographic data were analyzed at an academic core laboratory (CardHemo, Shanghai Jiao Tong University, Shanghai) using the QFR system (AngioPlus Galley 2.0, Pulse Medical, Shanghai, China) by certified analysts, with intra‐ and inter‐observer variability of 0.00±0.03 and 0.00±0.03 for μQFR analysis as previously reported. ¹⁰ Quantitative coronary analysis and μQFR were performed on pre‐PCI angiograms during the same procedure with the following steps: (1) the analyst selected an angiographic image run with minimal overlap and foreshortening and the software automatically detected the path of contrast dye filling, from which the contrast flow velocity was determined; (2) the lumen contours of the interrogated vessel and its side branches were automatically delineated and manually corrected if the contours did not follow the true lumen edge; (3) a second angiographic view was selected and the interrogated vessel was automatically delineated; (4) the software reconstructed the interrogated vessel in 3‐dimensional as well as the reference vessel using step‐down reference diameter function; (5) the software computed the μQFR based on the reconstructed vessel and the contrast flow velocity at every location along the interrogated vessel. ¹⁰ At the same step, quantitative coronary analysis parameters including minimal lumen diameter, percent diameter stenosis, lesion length, and reference vessel diameter were reported by the software, as well as the virtual μQFR pullback. The distal landmark of μQFR analysis was placed at the sensor position of the pressure wire on the angiographic images. All analyses were performed at core laboratory by 2 independent certified operators masked to the FFR values. Predicted μQFR with virtual stenting was calculated using pre‐PCI angiograms. ΔμQFR of all of the lesions with “virtually implant the stent” was obtained. “Virtually implant the stent” was marked with using the stent length at the exact location of the implantation site marked with a proximal and distal marker. The original vessel μQFR plus ΔμQFR of all treated lesions was the residual μQFR with virtual stenting (Figure 1).

First, a μQFR analysis was performed from before the percutaneous coronary intervention (PCI) with a 3‐dimensional vessel reconstruction (upper parts of the panel). Second, virtually treated zone was selected on the μQFR diagram (red gridlines) (lower parts of the panel). Third, predicted residual μQFR after virtually implanted a stent was obtained (upper right parts of the panel).