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Figure 1 This representative patient demonstrates a luminal enlargement after standard balloon angioplasty, after IVUS-guided balloon angioplasty and after stent implantation in single frame angiograms and IVUS images of the proximal LAD. However, the coronary flow reserve (ratio) remains impaired after each intervention (1.9, 1.9 and 1.5, respectively) as a result of the increased baseline blood flow velocity (BAPV) (26, 37 and 45 cm/s, respectively). Therefore, hyperemic blood flow velocity (PAPV) was used to assess the functional improvement after each intervention (49, 69 and 67 cm/s). In this patient, the maximal functional gain was accomplished after IVUS-guided balloon angioplasty as there was no additional increase in hyperemic blood flow after stent implantation. Note: baseline and hyperemic flow velocity signals are depicted on different y-axis scales during the procedure. IVUS = intravascular ultrasound; LAD = left anterior descending coronary artery; MLA = minimal lumen area.