CARDIOVASCULAR JOURNAL OF AFRICA • Volume 34, No 4, September/October 2023 202 AFRICA under the curve (AUC) for CIMT was 0.834 (95% CI: 0.768– 0.900; p = 0.0001). Using a cut-off value of 0.66 mm, CIMT predicted postoperative AKI with a sensitivity of 79.4% and specificity of 75.9%. Discussion In this study, we aimed to determine the association between pre-operative CIMT of the patients operated on for isolated CABG and early postoperative AKI. To our knowledge, this study is one of the few on this subject. The optimal cut-off value of 0.66 mm for the CIMT was found to be a strong and independent predictor of AKI. Moreover, elevated CRP level and ESR, PLR and NLR in the pre- and early postoperative periods were found to be associated with AKI. Therefore, pre-operative CIMT may be a useful, inexpensive and novel marker to predict AKI in the early postoperative period of isolated CABG. Pre- and early postoperative CRP, ESR, PLR and NLR may also be seen as early markers. Major adverse renal and cardiac events still exist as potential threats following cardiac surgery, despite the advances in surgical technique, anaesthetic management and supportive medical treatment.21 AKI is a common postoperative complication of cardiac surgery, associated with prolonged hospital stay and increased early morbidity and mortality rates, even for patients who do not progress to renal failure.22 The pathophysiology of AKI following cardiac surgery is complex and multifactorial, including renal ischaemia–reperfusion injury, exogenous and endogenous toxins, use of radiocontrast media, neurohormonal activation, metabolic factors, hypoproteinaemia, inflammation and oxidative stress.23 After cardiac surgery, AKI is seen at a rate of 5–48% and is associated with a 50% increase in early postoperative mortality.24 Hobson et al. reported AKI in 43% of cardiac surgery patients during in-hospital follow up.25 For standardisation, patients operated on for only isolated CABG using standard CPB were enrolled in our study, therefore postoperative AKI and acute renal failure occurred in 26.6 and 4.8% of the patients, respectively, which is in accordance with the literature. AKI incidence following cardiac surgery depends on its definition. The Risk, Injury, Failure, Loss of kidney function, and End-stage kidney disease (RIFLE) classification, Acute Kidney Injury Network (AKIN) criteria and KDIGO stages, are all practical predictors of AKI after CABG and/or heart valve operations.19,26 In our study, AKI was defined according to the KDIGO criteria. Since the role of inflammation on AKI has been shown in numerous studies, biomarkers of cellular inflammation, such as NLR and PLR, which are inexpensive and routinely tested, have been used frequently.15 Parlar et al. showed that elevated pre- and postoperative NLR and PLR levels were independently related to early postoperative AKI.16 In our study, we noted that pre- and postoperative NLR and PLR values were significantly higher in patients with AKI. Atherosclerosis is a chronic, multifactorial disease, generally affecting the entire arterial system.2 Since inflammation acts as a common base for physiological and pathological changes throughout the initiation and evolution of atherosclerosis, there has been vast experimental and clinical evidence regarding atherosclerosis as a chronic inflammatory disease.27 Leucocytes, mediators of host defence and inflammation, have been demonstrated in the earliest lesions of atherosclerosis, in both animal experiments and humans.28 CIMT, which shows both endothelial dysfunction and diffuse atherosclerosis, is one of the methods to determine the atherosclerotic process during the asymptomatic period.2 CIMT determination is a non-invasive, low-cost, easy and repeatable procedure to evaluate atherosclerosis.3 CIMT is not only a predictor of atherosclerosis, it also predicts myocardial infarction, stroke and future cardiovascular events.4 SahBandar et al. reported a strong correlation between inflammatory monocyte counts and CIMT.29 Significant correlations between IL-6 and CIMT in patients with the metabolic syndrome were also reported.30 Despite many studies, data regarding the relationship between CIMT and other indices of vascular injury are limited and controversial.3 Besir et al. emphasised that CIMT, which is correlatedwithmajor risks for atherosclerosis, such as age, visceral fatty tissue mass, fasting glucose level, and total and low-density lipoprotein cholesterol (LDL-C) levels in healthy adults, is a valuable test for the measurement of subclinical atherosclerosis and cardiovascular risk potential.31 A diffuse increase in CIMT is a predictive factor for arterial plaque formation. Genetic and acquired factors other than age are also considered to direct this progression; therefore, this reflects the relationship between diffuse intimal thickening and atheromatous lesions.20 In our study, the difference in CIMT in the AKI group was statistically significant, unlike the age difference. Recently, several prospective clinical studies have shown that even modest elevations in baseline CRP levels could predict cardiovascular events.32 CRP is the fastest elevated acute-phase reactant following inflammation or injury and is the fastest depleted during healing.33 CRP is considered an independent predictor of intima–media thickness.32 Shacham et al. reported on patients with ST-segment elevation myocardial infarction treated with primary percutaneous coronary intervention (PCI). The presence of a high-sensitivity CRP (hs-CRP) level > 9 mg/l prior to PCI was an independent risk factor for AKI.34 1 – Specificity 0 0.2 0.4 0.6 0.8 1.0 Sensitivity 1.0 0.8 0.6 0.4 0.2 0.0 Fig. 1. ROC curve analysis of CIMT to predict postoperative AKI.
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