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

Abstract

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. 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. 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. 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.