Serum PCSK9 levels predict the occurrence of acute coronary syndromes in patients with severe carotid artery stenosis

Background: The pharmacological inhibition of Proprotein Convertase Subtilisin/Kexin type 9 (PCSK9) has shown to dramatically impact on low-density lipoprotein-cholesterol (LDL-C) levels and associated cardiovascular (CV) diseases. However, the potential use of PCSK9 serum levels as a CV risk biomarker remains to be clarified. Methods: 189 patients with severe carotid artery atherosclerosis undergoing carotid endarterectomy (CEA) and whose clinical records and serum sample aliquots for PCSK9 level measurement were available both directly before CEA and at 24-month follow-up were included in the present pilot study. The study endpoint was to determine whether PCSK9 serum levels prior to CEA would predict the occurrence of acute coronary syndromes (ACS) at 24-month follow-up. Results: PCSK9 serum levels were significantly accurate in predicting ACS at 24-month follow-up, as assessed by ROC curve analysis (AUC: 0.719 [95% CI 0.649–0.781]). According to the cut-off point indicated by Youden's index, PCSK9 values >431.3 ng/mL were correlated with a higher risk of ACS occurrence (Log Rank test, p = 0.0003). At Cox regression analysis, the predictive ability of high serum PCSK9 was confirmed also after adjustment for age, gender, baseline statin treatment and active smoking, dyslipidemia, and chronic coronary artery disease (HR 17.04 [95% CI 3.34–86.81]; p = 0.001). Conclusions: High serum PCSK9 levels predict ACS occurrence at 24-month follow-up after CEA in patients with severe carotid artery stenosis. Larger clinical studies are needed to evaluate whether PCSK9 serum levels could be used towards predicting the risk of ACS in patients with advanced carotid atherosclerosis.