Intravascular ultrasound (IVUS)-defined focal residual lesions in vessels with angiographically successful percutaneous coronary intervention (PCI) and post-PCI fractional flow reserve (FFR) <0.90 were poorly to moderately identified using nonhyperemic pressure ratio (NHPR) and moderately to well identified using FFR. However, well-expanded and underexpanded stents cannot be distinguished via the in-stent pressure gradients, a new subanalysis shows.