Localized Elevation of Wall Shear Stress Is Linked to Recent Symptoms in Patients with Carotid Stenosis

Abstract

<b><i>Background:</i></b> Estimation of symptomatic and asymptomatic carotid atherosclerosis differences can be the basis for prevention and management of carotid artery stenosis disease. In clinical practice, carotid plaque vulnerability is assessed only on the basis of luminal stenosis. However, the evolution of carotid plaque from an asymptomatic state to a symptomatic one is a complex process and the underlying hemodynamic mechanisms are unknown. We aimed to investigate the differences in hemodynamic parameters between patients with recently symptomatic carotid stenosis and asymptomatic ones. <b><i>Methods:</i></b> Hemodynamic simulations were performed on 26 carotid plaques from 25 patients with carotid artery stenosis ≥50%, 16 of whom had recent cerebrovascular ischemic events. Using human-specific flow parameters and 3D reconstruction of carotid computed tomography angiography images, we assessed hemodynamic characteristics such as wall shear stress (WSS), time-averaged WSS (TAWSS), oscillatory shear index, and relative residence time (RRT) during the cardiac cycle in patients with and without symptoms. <b><i>Results:</i></b> We found that symptomatic carotid stenosis patients had greater local TAWSS (99.59 ± 26.29 vs. 60.40 ± 20.46 dyn/cm<sup>2</sup>, <i>p</i> = 0.0007) and maximal WSS (116.65 ± 39.11 vs. 68.28 ± 23.67 dyn/cm<sup>2</sup>, <i>p</i> = 0.003), but lower RRT (0.019 ± 0.006 vs. 0.013 ± 0.069 s, <i>p</i> = 0.049), than asymptomatic patients, but this hemodynamic difference was not associated with carotid stenosis severity (<i>p</i> = 0.70). Patients with transient ischemic attack (TIA) or stroke had higher local TAWSS and WSSmax than patients with asymptomatic stenosis (<i>p</i> < 0.05). Subgroup analysis showed that there was no statistical difference in local hemodynamic variables between TIA and stroke patients with carotid artery stenosis. <b><i>Conclusions:</i></b> Patients with carotid artery stenosis are more likely to experience acute ischemic cerebrovascular accidents if they have higher WSS. Simultaneous assessment with hemodynamic parameters like WSS along with stenosis severity may aid risk stratification in patients with asymptomatic carotid artery stenosis.

Characteristics and evaluation of atherosclerotic plaques: an overview of state-of-the-art techniques

“…Compared with static simulations, TA-WSS can reflect the average changes in WSS across cardiac cycles (105). Studies have shown that regions with high TA-WSS and low oscillatory shear index have larger necrotic core sizes, larger macrophage areas, and thinner fibrous caps in (167).…”