Wall shear stress and oscillatory shear index are independently associated with complicated carotid artery plaques.

Aims Complicated carotid artery plaques (cCAP), characterized by intraplaque haemorrhage (IPH), thin or ruptured fibrous caps, and/or superimposed thrombi pose a high stroke risk. The role of individual carotid geometry and local haemodynamics - such as wall shear stress (WSS) and oscillatory shear index (OSI) - in the development of cCAP is insufficiently understood. This study aimed to identify imaging- and blood-based biomarkers associated with the presence of cCAP to improve individual risk stratification.Methods And Results We prospectively recruited 141 consecutive patients with 20-80% ICA stenosis (NASCET criteria) at a tertiary stroke centre. Using 3D high-resolution multi-contrast MR plaque imaging and 4D flow MRI, we assessed plaque composition, vascular geometry, and local haemodynamics, alongside blood biomarker profiling. Multivariable logistic regression models determined independent associations with cCAP. We identified cCAP in 64/220 included carotid arteries (29.1%) among 57/129 patients (44.2%; 30.2% women, 72.8 ± 8.68 years). Female gender was inversely associated with cCAP (OR 0.32, p = 0.02), adjusting for age, wall thickness, cardiovascular risk factors and geometric and haemodynamic parameters. Patients with cCAP showed a lower ICA-CCA ratio (p = 0.018). Increased systolic WSS (OR 1.54, p = 0.020) and low OSI (OR 0.67, p = 0.044) were independently correlated with cCAP after adjustment. Blood biomarkers showed no significant correlation.Conclusion In patients with up to 80% ICA stenosis, male gender, elevated systolic WSS and reduced OSI were independently associated with the presence of cCAP, with group differences noted for ICA/CCA ratio. Our findings highlight the importance of geometric and haemodynamic biomarkers for individual stroke risk stratification.