High-sensitivity C-reactive protein in high-grade carotid stenosis: risk marker for unstable carotid plaque.

ABSTRACT

OBJECTIVES: Increasing evidence points to the inflammatory character of atherosclerosis, and several parameters of inflammation have been proposed as cardiovascular risk markers. We analyzed associations among serum high-sensitivity C-reactive protein (hs-CRP) concentrations, carotid plaque structure, and immunocytology, and neurologic symptoms in patients with high-grade carotid stenosis. METHODS: This was a cross-sectional study in a referral center and institutional practice in hospitalized patients. The study included 62 patients with greater than 70% carotid stenosis treated surgically; 58% of patients had symptoms, and 42% did not. Serum hs-CRP concentrations were determined 48 hours before surgery; levels greater than 10 mg/L were considered pathologic. Histopathologic analysis (stable or unstable) and immunohistochemistry (macrophage count, T lymphocytes, activated T lymphocytes) were carried out on the atherosclerotic plaques. RESULTS: Median hs-CRP values were 7.6 mg/L (range, 0-165 mg/L). Median hs-CRP concentrations were higher in patients with unstable plaque (53.2%) than in patients with stable plaque (46.7%) 27.1 mg/L (range, 1.8-165 mg/L) versus 4.1 mg/L (range, 0.3-56 mg/L) (P <.001). Among patients with symptomatic disease, 81% had CRP concentrations significantly higher than CRP concentrations in patients with asymptomatic disease (P <.001). A statistically significant association was found between hs-CRP levels and the presence of macrophages (Spearman rank correlation [rho], 0.61, P <.001) and T lymphocytes in the plaque (Spearman rank correlation [rho], 0.52, P <.001). At logistic regression analysis, neurologic event and macrophages in the plaque were independently associated with unstable plaque. CONCLUSIONS: Increased hs-CRP levels may be related to the presence of macrophages and T lymphocytes in plaque, which is associated with the phenomena of instability that can lead to development of an ischemic event. Thus determination of circulating hs-CRP levels may be a useful additional marker of risk in patients with high-grade carotid stenosis.