CARDIOVASCULAR JOURNAL OF AFRICA • Volume 34, No 5, November/December 2023 278 AFRICA Is pre-operative monocyte count-high-density lipoprotein ratio associated with postoperative acute kidney injury in isolated coronary artery bypass grafting? Hüseyin Şaşkın Abstract Objective: Monocyte-to-high-density lipoprotein cholesterol ratio has emerged as an indicator of inflammation and oxidative stress in recent years. The aim of this study was to evaluate the association of monocyte-to-high-density lipoprotein ratio with postoperative acute kidney injury in isolated coronary artery bypass grafting. Methods: A total of 954 patients (672 males, mean age 60.8 ± 8.2 years), operated on between June 2014 and June 2022, at the same centre by the same team, for isolated coronary artery bypass grafting with cardiopulmonary bypass, whose preoperative serum creatinine level was < 1.5 mg/dl, were enrolled in the study. Patients were placed in group 1 if they had acute kidney injury in the early postoperative period (n = 161) and group 2 comprised those without (n = 793). Univariate and subsequent multivariate logistic regression analysis were done to determine significant clinical factors, and independent predictors of acute kidney injury. Results: Pre-operative monocyte count (p = 0.0001), monocyte count-high-density lipoprotein cholesterol ratio (p = 0.0001), C-reactive protein (p = 0.0001), erythrocyte sedimentation rate (p = 0.0001), mean platelet volume (p = 0.0001) and postoperative first- and third-day C-reactive protein levels (p = 0.0001) were significantly increased in group 1. Multivariate logistic regression analysis revealed that pre-operative elevated monocyte count (p = 0.0001), monocyte-high-density lipoprotein ratio (p = 0.0001), erythrocyte sedimentation rate (p = 0.0001), postoperative first-day C-reactive protein level (p = 0.0001), postoperative first-third day erythrocyte sedimentation rate (p = 0.002, p = 0.004, respectively) and mean platelet volume (p = 0.02, p = 0.0001, respectively) were independent predictors of early postoperative acute kidney injury in patients who had undergone isolated coronary artery bypass grafting. Conclusion: Pre-operative monocyte-high-density lipoprotein cholesterol ratio was found to be an independent predictor of acute kidney injury in the early postoperative period of isolated coronary artery bypass grafting. Keywords: coronary artery bypass grafting surgery, monocyteto-high-density lipoprotein cholesterol ratio, acute kidney injury Submitted 17/10/22, accepted 28/10/22 Published online 24/11/22 Cardiovasc J Afr 2023; 34: 278–284 www.cvja.co.za DOI: 10.5830/CVJA-2022-055 Coronary artery bypass grafting (CABG) surgery is still the goldstandard treatment method for multi-vessel or left main coronary artery disease (CAD).1 With the developments in cardiopulmonary bypass (CPB) technology in recent years, these surgeries can be done with very low mortality and morbidity rates.2 As an important pathology, acute kidney injury (AKI) often follows cardiac surgery, resulting in extended intensive care unit (ICU) and hospital stays, and increased expenses and morbidity and mortality rates.3 AKI is a common complication after cardiac surgery, with an incidence of 19–42%, and renal replacement therapy may be required in 1–3% of these patients.4 The risk factors and pathophysiology of AKI following CABG have been described in the literature and have been the subject of many studies.3 The pathophysiology of AKI is complex and multifactorial; the injury site is typically the tubular cells, and toxins (exogenous and endogenous), inflammation, ischaemia– reperfusion injury, neurohormonal activation, metabolic factors and oxidative stress play a role in its aetiopathogenesis.5 Various biomarkers have been used recently to diagnose AKI, as one of the important causes of morbidity and mortality in the early postoperative period of CABG.3 Including white blood cell (WBC) count, leukocyte subtypes, platelets, mean platelet volume (MPV), C-reactive protein (CRP), neutrophil-to-lymphocyte ratio (NLR) and platelet-to-lymphocyte ratio (PLR), various inflammatory biomarkers have been shown to exist as important prognostic determinants in various cardiovascular diseases.6 Parlar et al. showed that increased NLR and PLR levels in the pre-operative and early postoperative periods were directly related to and independent biomarkers of the development of AKI in the early postoperative period.7 Monocytes are the main source of pro-inflammatory cytokines, and in atherosclerosis, modified low-density lipoprotein cholesterol (LDL-C) is removed by macrophages. These accumulate in the vessel wall and induce the release of inflammatory cytokines in the inflamed tissue, resulting in the production of inflammatory cholesterol ester-loaded plaque.8 High-density lipoprotein cholesterol (HDL-C), on the other hand, has anti-inflammatory, antioxidant and antiatherosclerotic effects by neutralising the pro-inflammatory and pro-oxidant effects of monocytes by inhibiting the migration of macrophages and LDL-C oxidation, in addition to cholesterol exit from these cells.9 The monocyte-HDL-C ratio (MHR) is a new and inexpensive marker of inflammation and can be easily obtained by Cardiovascular Surgery Clinic, Derince Training and Research Hospital, Health Sciences University, Kocaeli, Turkey Hüseyin Şaşkın, MD, sueda_hs@yahoo.com
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