PCSK9 in relation to coronary plaque inflammation: Results of the ATHEROREMO-IVUS study

Background and aims: Experimental studies have suggested that proprotein convertase substilisin/kexin type 9 (PCSK9) might directly promote inflammatory processes contributing to atherosclerosis by mechanisms independent of low-density lipoprotein (LDL) cholesterol levels. This study aims to investigate the association between serum PCSK9 levels and the fraction and amount of necrotic core tissue in coronary atherosclerotic plaque, as assessed by intravascular ultrasound virtual histology (IVUS-VH) imaging. Methods: Between 2008 and 2011, IVUS-VH imaging of a non-culprit coronary artery was performed in 581 patients who underwent coronary angiography for acute coronary syndrome (ACS) or stable angina. PCSK9 concentrations were measured in serum samples that were drawn prior to coronary angiography. None of the patients received PCSK9 inhibitors. Results: After adjustment for established cardiac risk factors, statin use and serum LDL cholesterol, serum PCSK9 levels were linearly associated with the fraction of plaque consisting of necrotic core tissue (β = 1.24% increase per 100 μg/L increase in PCKS9, 95%CI 0.55-1.94, p = 0.001) and with the absolute volume of necrotic core tissue (β = 0.09, 95%CI 0.01-0.18, p = 0.033), but were not significantly associated with plaque burden (p = 0.11), plaque volume (p = 0.22) or the presence of IVUS-VH-derived thin-cap fibroatheroma lesions (p = 1.0). Conclusion: Serum PCSK9 levels were linearly associated with the fraction and amount of necrotic core tissue in coronary atherosclerosis, independently of serum LDL cholesterol levels and statin use. Therefore, PCSK9 may be an interesting therapeutic target for the treatment of atherosclerotic disease beyond LDL cholesterol regulation.