Table 2. New physiological indexes representing plaque vulnerability and lesion-specific hemodynamics properties.
| Hemodynamic metrics | Derivation | Physiological implications | Clinical evidence |
|---|---|---|---|
| ΔFFR or ΔNHPR | Proximal FFR or NHPR − Distal FFR or NHPR | • A lesion-specific pressure drop | • ΔFFR was correlated with lesion-specific hemodynamic properties surrounding a plaque, such as pressure gradient, wall shear stress, or axial plaque stress.53) |
| • High ΔFFR (≥0.06) was associated with a higher risk of ACS and long-term clinical events.57),74) | |||
| PPG |
|
• A physiological disease pattern (focal vs. diffuse) of a vessel | • Revascularization for focal physiological disease, defined by high PPG, was related to better improvement in post-PCI FFR and larger minimal stent area.76) |
| RWSmax | Maximal RWS  along the lesion segment |
• A quantified coronary strain of a lesion | • RWSmax was correlated with OCT-derived lipid-rich plaque and a prevalence of TCFA.77) |
| • Among intermediate coronary lesions, high RWSmax predicted lesion progression.78) | |||
| • In deferred lesions with QFR >0.80 in the FAVOR III China study, high RWSmax was predictive of 1-year clinical events.79) |
ACS = acute coronary syndrome; FFR = fractional flow reserve; NHPR = non-hyperemic pressure ratio; OCT = optical coherence tomography; PCI = percutaneous coronary intervention; PPG = pullback pressure gradient; QFR = quantitative flow ratio; RWSmax = maximal radial wall strain; TCFA = thin cap fibroatheroma.