Interplay between intracoronary imaging-derived plaque morphologies and pathophysiological stenosis patterns determined by quantitative flow ratio-derived pullback pressure gradient

Background The association between morphological plaque features and pathophysiological disease patterns remains poorly understood. Purpose This study aimed to investigate the relevance of high-risk coronary plaque characteristics, as identified by optical coherence tomography (OCT) and near-infrared spectroscopic intravascular ultrasound (NIRS-IVUS), in relation to varying degrees of pathophysiological coronary atherosclerotic disease patterns, assessed using the quantitative flow ratio (QFR)-derived pullback pressure gradient (PPG). Methods We evaluated 158 de novo coronary lesions in 158 patients with chronic coronary syndrome who underwent OCT, NIRS-IVUS, and QFR-PPG assessments. Lesions were categorized into tertiles based on QFR-PPG values. OCT findings included minimal lumen area (MLA), plaque rupture, thin-cap fibroatheroma (TCFA), layered plaque, and calcification. OCT-derived TCFA was defined as a lipid-rich plaque (lipid arc ≥ 90 degrees) with a fibrous cap thickness < 80 µm. NIRS-IVUS findings included MLA, maximum plaque burden, remodeling index, echo attenuation, and maximum lipid core burden index over a 4-mm segment in the culprit lesion (max LCBI4mm). IVUS-derived TCFA was identified by the presence of echolucent zones and/or ultrasound attenuation in areas of positive remodeling. Clinical demographics and OCT and NIRS-IVUS findings were compared across the QFR-PPG tertiles. Results In this cohort, the median QFR-PPG value was 0.74 (interquartile range [IQR]: 0.62–0.82). The median age was 69.5 years (IQR: 62.0–74.8), and 79.7% (126/158) of patients were male. QFR-PPG tertiles were defined as follows: 1st tertile (Diffuse group): QFR-PPG < 0.66, 2nd tertile (Intermediate group): 0.66 ≤ QFR-PPG ≤ 0.80, 3rd tertile (Focal group): QFR-PPG > 0.80. Clinical demographics showed no significant differences across tertiles. On OCT, MLA, lipid arc, fibrous cap thickness, and the prevalence of plaque rupture and TCFAOCT did not vary with the QFR-PPG index. However, the prevalence of layered plaque demonstrated graded differences across tertiles: 64.8% in the Diffuse group, 50.9% in the Intermediate group, and 37.3% in the Focal group (P for trend < 0.01). Similarly, calcium angle showed graded differences: 103 degrees (IQR: 0–218) in the Diffuse group, 82 degrees (IQR: 0–188) in the Intermediate group, and 38 degrees (IQR: 0–98) in the Focal group (P for trend < 0.01). On NIRS-IVUS, maximum plaque burden, prevalence of IVUS-derived TCFA, and maxLCBI4mm showed no differences across tertiles. Multivariable linear regression analysis indicated that OCT-derived layered plaque and calcium angle were independently associated with the QFR-PPG index. Conclusion Multimodal intracoronary imaging revealed that pathophysiological atherosclerotic patterns were associated with the presence of layered plaques and calcium burden, rather than lipid-related unstable plaque features.