Figure 6.

Case examples of false negative and false positive residual QFR results. Case 1 displays a false negative residual QFR result. Post-PCI FFR remained suboptimal after a successful intervention in proximal to mid LAD (1a-b). Residual QFR estimated a post-PCI FFR of 0.98, and there was no significant pressure drop observed beside that of the treated lesion (1c–e). Contrary, case 2 shows a satisfactory PCI result of the RCA (2a-b). However, residual QFR predicted a suboptimal PCI result based on the presence of additional stenosis that proved not to be functionally relevant (2c–e). FFR, fractional flow reserve; PCI, percutaneous coronary intervention; QFR, quantitative flow ratio; LAD, left anterior descending artery; RCA, right coronary artery.