High wall shear stress is related to complicated AHA lesion type VI plaques in mild to moderate internal carotid artery stenosis – a 3D cardiovascular MRI study

BACKGROUND AND PURPOSE: Complicated American Heart Association (AHA) lesion type VI plaques (cCAPs), characterized by the presence of intraplaque hemorrhage, surface defect or thrombus, are strongly associated with ischemic stroke and stroke recurrence. Hemodynamics seem to play a relevant role for their development. Thus, we investigated the association of 4D flow-MRI derived local wall shear stress (WSS) and oscillatory shear stress (OSI) with the presence of cCAPs in patients with mild to moderate internal carotid artery (ICA) stenosis.

MATERIALS AND METHODS: From a prospective and consecutive cross-sectional study with 121 patients with high cardiovascular risk, 39 patients (49 carotid arteries) demonstrated a 10-50% ICA-stenosis and were included in this analysis. Plaque composition was determined according to the modified AHA classification of lesions by high-resolution multi-contrast 3T-MRI. We determined WSS (minimum, mean and maximum) and OSI in vivo by 4D flow-MRI at different locations within the stenosis (upstream, stenosis center and downstream). We studied the association of each hemodynamic parameter with the presence cCAPs by logistic regression analysis adjusted for age, sex and plaque thickness.

RESULTS: 11 (22.4%) of the 49 ICA-stenosis in our cohort showed cCAP. WSS and OSI at the beginning of the stenosis did not differ between complicated and stable plaques. By contrast, WSS was significantly higher in the stenosis center and poststenotic region in cCAPs. OSI was significantly higher in the stenosis center of stable plaques. Logistic regression analysis revealed a significant association for WSS_mean (OR per SD increase 1.97, 95%-CI 1.14-3.39, p=0.015) and for WSS_max (OR per SD increase 1.84; 95%-CI 1.10-3.08; p=0.020), but not for WSS_min and OSI with the presence of cCAPs.

CONCLUSIONS: Higher wall shear stress in ICA stenosis was significantly associated with the presence of cCAPs underlining the potential role of hemodynamics in their development.

ABBREVIATIONS: cCAP, complicated carotid artery plaque; WSS, wall shear stress; OSI, oscillatory shear index.