The symptomatic carotid plaque

Background-The natural histories of equally severe symptomatic and asymptom atic carotid stenoses are very different, which suggests dichotomy in plaqu e behavior. The vascular biology of the symptomatic carotid plaque is prese nted in this review. Summary of Review-Histology studies comparing asymptomatic and symptomatic plaques were identified from MEDLINE. Reports in which stenosis severity wa s not stated or not similar for symptomatic and asymptomatic patients were excluded. In vitro studies and reports from the coronary circulation were r eviewed with regard to the vascular biology of the plaque. Histology studie s comparing carotid plaques removed from symptomatic and asymptomatic patie nts reveal characteristic features of unstable plaques: surface ulceration and plaque rupture (48% of symptomatic compared with 31% of asymptomatic, P <0.001), thinning of the fibrous cap, and infiltration of the cap by greate r numbers of macrophages and T cells, In vitro studies suggest that macroph ages and T cells release cytokines and proteinase, which stimulate breakdow n of cap collagen and smooth muscle cell apoptosis and thereby promote plaq ue rupture. Conclusions-Infiltration of inflammatory cells to the surface of carotid pl aques may be a critical step in promoting plaque rupture and resultant embo lization or carotid occlusion. Further understanding of cell recruitment an d behavior in carotid atherosclerosis may allow better detection of unstabl e plaques and therapeutic methods of plaque stabilization.