Histological Analysis of Carotid Plaques: The Predictors of Stroke Risk.

OBJECTIVES:The morphology and histological structure of the atherosclerotic plaque seem critical to its stability. Our study aimed to identify the epidemiological, morphological and histological parameters associated with stable and unstable plaques. MATERIALS AND METHODS:The study included 280 plaques harvested from 269 consecutive patients. Epidemiological and demographic data were recorded as well as the histological features of plaque, i.e. calcifications, myxoid changes, bleeding into plaque, presence of thrombus, inflammation, macrophages, giant cell reaction, siderophages, neovascularization and plaque ossification. All specimens were classified according to the American Heart Association (AHA). RESULTS:Monofactorial analysis identified three significant histological predictors for the symptomatic plaque: a plaque with a large necrotic core (odds ratio, OR=2.0, p = 0.03), thrombosis (OR=3.7, p = 0.01) and the formation of foamy macrophages (OR=2.0, p = 0.01). Multifactorial logistic regression revealed that the presence of foamy macrophages (OR=1.9, p = 0.03) and thrombosis (OR=3.5, p = 0.02) were significant predictors of symptomatic stenosis. Symptomatic plaques were significantly more frequently classified as AHA type VI than AHA type IV-V compared to asymptomatic ones (OR=1.8, p = 0.03). CONCLUSIONS:Our study shows that no single histological feature, except for the presence of foamy macrophages and thrombosis on the plaque, is predictive of plaque instability. Rather, a complex plaque structure (AHA type VI) is predictive of plaque instability. Our findings should be kept in mind during the assessment of non-invasive imaging and stroke risk estimation.