Relationship between monocyte-to-lymphocyte ratio and coronary plaque vulnerability in patients with acute coronary syndrome: an optical coherence tomography study

Abstract Background The importance of monocyte-to-lymphocyte ratio (MLR) has been indicated in the initiation and progression of coronary artery disease (CAD). However, few previous researches demonstrated the relationship between MLR and plaque vulnerability. We aimed to investigate coronary plaque vulnerability in patients with acute coronary syndrome (ACS) by optical coherence tomography (OCT). Methods A total of 72 ACS patients who underwent coronary angiography and OCT test in Beijing Anzhen hospital were included in this retrospective study. The plaque vulnerability and plaque morphology were assessed by OCT. Results The coronary plaque in high MLR group exhibited more vulnerable features, characterizing as thinner thickness of fibrous cap (FCT)(112.37 ± 60.24 vs 153.49 ± 73.29 μm, P = 0.013), greater maximum lipid core angle (167.36 ± 62.33 vs 138.79 ± 56.37°, P = 0.010) and longer lipid plaque length (6.34 ± 3.12 vs 4.50 ± 2.21mm, P = 0.041). A prominently negative liner relation was found between MLR and FCT (R = 0.225, P < 0.005). Meanwhile, the incidence of OCT-detected thin cap fibro-atheroma (TCFA) (44.7% vs 18.4%, P = 0.014) and plaque rupture (36.8% vs 13.2%, P = 0.017) were higher in high MLR group. Most importantly, multivariable logistic regression analysis showed MLR level was related to the presence of TCFA (OR:3.316，95%：1.448-7.593，P = 0.005). MLR level could differentiate TCFA with a sensitivity of 72.0% and a specificity of 66.1%. Conclusion Circulating MLR level has potential value in identifying the presence of vulnerable plaque in patients with ACS. MLR, as a non- invasive biomarker of inflammation, may be valuable in revealing plaque vulnerability. Key words Monocyte-to-lymphocyte ratio, Optical coherence tomography, Plaque vulnerability