Central Illustration. Importance of assessment of pre-PCI pathophysiological CAD pattern in addition to stent optimisation by intracoronary imaging.

The target vessel with diffuse disease pattern in pre-PCI pathophysiological assessment achieved an expansion index ≥80% by stent optimisation using IVUS. However, the post-PCI µQFR was still <0.91 due to a residual pressure drop in non-stented segments, while the µQFR-trans-stent gradient was 0.00. This case also had characteristics of diffuse disease in intracoronary imaging, such as a small MSA, small reference area, and large plaque burden in the stented segment. CAD: coronary artery disease; dµQFR/ds: instantaneous µQFR ratio gradient per unit length; MSA: minimal stent area; PCI: percutaneous coronary intervention; PPG: pullback pressure gradient; µQFR: Murray law-based quantitative flow ratio