Higher leukocyte count is associated with lower presence of carotid lipid-rich necrotic core: a sub-study in the Plaque At RISK (PARISK) study

Background: Increasing evidence suggests that inflammation inside the vessel wall has a prominent role in atherosclerosis. In particular in carotid atherosclerosis, vulnerable plaque characteristics are strongly linked to an increased stroke risk. An association between leukocytes and plaque characteristics has not been investigated before and could help with gaining knowledge of inflammation in plaque vulnerability, which could contribute to a new target for intervention. In this study, we investigated the association of leukocyte count with carotid vulnerable plaque characteristics. Methods: All patients from the Plaque At RISK (PARISK) study whom had complete data on leukocyte count and CTA- and MRI-based vulnerable plaque characteristics, were included. Univariable logistic regression was used to detect associations of leukocyte count with the separate vulnerable plaque characteristics (intra-plaque haemorrhage (IPH), lipid-rich-necrotic core (LRNC), thin or ruptured fibrous cap (TRFC, plaque ulceration and plaque calcifications). Subsequently, other known risk factors for stroke were included as covariates in a multivariable logistic regression model. Results: 161 patients were eligible for inclusion in this study. Forty six (28.6%) of these patients were female with a mean age of 70 [IQR 64-74]. An association was found between higher leukocyte count and lower prevalence of LRNC (OR 0.818 (95% CI 0.687-0.975), while adjusting for covariates. No associations were found between leucocyte count and presence of IPH, TRFC, plaque ulceration or calcifications. Conclusions: Leukocyte count is inversely associated with presence of LRNC in the atherosclerotic carotid plaque in patients with a recently symptomatic carotid stenosis. The exact role of leukocytes and inflammation in plaque vulnerability deserves further attention.