Ivan Melnikov ^1,2* Sergey Kozlov ¹ Sergey Okhota ¹ Olga Saburova ¹ Yuliya Avtaeva ¹ Tatiana Kuznetsova ¹ Konstantin Guria ¹ Lyudmila Prokofieva ¹ Tatiana Riazantseva ¹ Shang-Rong Ji ³ Yi Wu ⁴ Zufar Gabbasov ⁵

• ¹ National Medical Research Centre of Cardiology named after academician E.I. Chazov of the Ministry of Health of the Russian Federation, Moscow, Moscow Oblast, Russia
• ² Institute of Biomedical Problems, Russian Academy of Sciences (RAS), Moscow, Moscow Oblast, Russia
• ³ Lanzhou University, Lanzhou, Gansu Province, China
• ⁴ Xi'an Jiaotong University, Xi'an, China
• ⁵ National Medical Research Center for Cardiology, Ministry of Health of the Russian Federation, Moscow, Russia

Introduction: Chronic inflammation is a major risk factor for coronary artery disease (CAD). Currently, the inflammatory cardiovascular risk is assessed via C-reactive protein (CRP) levels measured using a high-sensitivity assay (hsCRP). Monomeric CRP (mCRP) is a locally produced form of CRP that has emerged as a potential biomarker of inflammation. Aim: This study investigated whether mCRP levels are associated with premature CAD. Materials and methods: This study comprised 103 participants of both sexes, including 50 patients 56±7 years old with premature CAD and 53 patients 51±10 years old without CAD. CAD was verified using coronary angiography, hsCRP levels were measured using a standard assay, and . mCRP levels were measured using fluorescent cytometric beads conjugated with an anti-mCRP antibody. Results: The levels of hsCRP were 0.99 (0.59; 3.10) mg/L vs. 0.63 (0.35; 1.85) mg/L (p = 0.067), and mCRP 6.84 (4.20; 13.78) µg/L vs. 2.57 (0.32; 5.66) µg/L (p <0.001) in patients with CAD vs. patients without CAD, respectively. There was a weak positive correlation between the mCRP and hsCRP levels (ρ = 0.214; p = 0.030). hsCRP levels were below 2.0 mg/L (i.e., there was no residual inflammatory cardiovascular risk) in 70% of patients with CAD and 79% of patients without CAD (p = 0.365). mCRP levels differed between the groups of patients, with hsCRP levels below 2.0 mg/L: 5.14 (4.07; 10.68) µg/L vs. 2.77 (0.53; 5.00) µg/L in patients with or without CAD, respectively (p <0.001). Logistic regression analysis demonstrated that mCRP levels were independently associated with premature CAD. The adjusted odds ratio was 1.18 (95% CI 1.06-1.33, p = 0.004) per each µg/L increase in mCRP levels. Conclusion: Higher mCRP levels were associated with premature CAD, independent of hsCRP levels and traditional risk factors.