European Journal of Cardiovascular Medicine

Endothelial Dysfunction (ED) is one of the major factors for the development and clinical appearance of metabolic syndrome and its complications. A high levels of blood glucose and further progress to microvascular and macrovascular complications considerably increase the morbidity and mortality. It might be caused by many factors such as dyslipidaemia, oxidative stress, inflammation and other factors too. Lipid abnormality is the major factor to cause ED; especially LDL particles are more susceptible to oxidation. These oxidised LDL particles reduce the availability of NO and impair endothelial function. This emerges in a “positive feedback loop” in which inflammatory factors promote monocyte and T-cell adhesion, foam cell formation, extracellular matrix digestion and vascular smooth muscle migration and proliferation leading to atherosclerosis ^(1,2). Dyslipidaemia is one of the most important factors for CAD. A growing body of evidence indicates that decreases in high-density lipoprotein cholesterol (HDL-C) and increases in total cholesterol (TC), low-density lipoprotein cholesterol (LDL-C), and triglyceride (TG) may contribute to the progression of atherosclerosis ^(3,4). Among them, LDL-C is considered to be the primary target for therapy. However, after reducing LDL-C to the recommended levels, an ∼50% remnant cardiovascular risk remains, thus encouraging researchers to find new CAD predictors. In recent years, researchers have focused on a new comprehensive lipid index, the atherogenic index of plasma (AIP), which might comprehensively reflect the balance between atherogenic and anti-atherogenic factors. Recently, AIP has been shown to be a strong marker for predicting the risk of CAD ⁽⁵⁾. In prospective study, researcher have found that AIP predicted CAD independently in a Turkish population. However, the results were inconsistent. Nansseu et al ⁽⁵⁾ revealed that AIP was not an independent factor determining the impact of the risk of cardiovascular disease in Cameroonian postmenopausal women. In a prospective cohort study, Hartopo et al⁽⁶⁾ investigated the relationship between the AIP value and major adverse cardiovascular events during intensive hospitalization in patients with acute myocardial infarction (AMI). Since, atherogenic Plasma index have initiate endothelial disfunction and causes cardiovascular complications. The present study has been designed to determine lipid alteration and atherogenic indices   as a strong predictor in coronary complication.

An analytical type of study was conducted in the department of Biochemistry, GS Medical College & Hospital, Hapur, Uttar Pradesh after getting approval from institutional ethical committee. Written and verbal consent was taken from every participated individual. A total of 60 Subjects with an age group of 25-65 years of either gender was enrolled for this study. Out of 60 subjects 30 were subjects with confirm diagnosed cases of coronary artery diseases from the cardiology units of GS Hospital and 30 were healthy individuals in and around the hospital campus. Subjects with liver diseases, renal diseases, diabetes, hypertension, obesity, and other metabolic syndrome were excluded from the study.

Blood collection and processing: - Under septic condition 3ml blood were drawn from every individual in a plane tube. The blood samples were separated as serum/plasma by centrifugation at 3000 rpm for 15 minutes. 3 mL sample was transferred to cup for the estimation of lipid profile.

Biochemical Analysis and index calculation:

Lipid profile (Total Cholesterol, TG and HDL) was estimated by well-established methods (Cholesterol by cholesterol esterase and peroxidase, TG by glycerol phosphate oxidase and peroxidise and HDL-c by Immunoinhibition, 2 reagent method) in fully autoanalyzer. LDL and Very Low-Density Lipoprotein (VLDL) were calculated by standard Friedwald’s equation. VLDL cholesterol concentrate=TG/5 LDL cholesterol concentrate=Total cholesterol-(VLDL+HDL). Atherogenic index of plasma was calculated by using formula log (TG/HDL-c) ⁽⁷⁾.

Statistical analysis:

Data analysis was done by using Microsoft Excel and the Statistical Package for the Social Sciences (SPSS) software version 21.0. Data were represented in the form of Mean and Standard Deviation “Kruskal-Wallis” test was performed for variables between the study groups. A p-value less than 0.05 was considered for the statistically significant. Pearson correlation was done between study parameters.

Table-1: Comparative analysis of parameters in Cases and controls

p value ≤ 0.05 is considered statistically significant

^a Confirmed cases of CAD

^b Healthy Individual

It is well known that endothelial dysfunction is a powerful risk factor for diabetes as well as CVD. Though, in all the condition dyslipidaemia is found to be a more powerful risk factor. long-term hyperglycaemia causes generalized vascular endothelial damage, which reduces functional lipoprotein lipase, leading to increase in triglycerides and a decrease in HDL. Increased levels of and triglycerides, cholesterol, LDL mediate the progression of atherosclerosis ⁽⁸⁾. Lipid ratios and AIP have been reported to indicate atherogenic dyslipidaemia. In the present study we observed significant elevation in lipid parameters, lipid ratio, and atherogenic index. Similar findings were reported by Suchitra MM et al ⁽⁹⁾ in their study to assess atherogenic dyslipidaemia in T2DM and diabetic nephropathy patients. Various lipid and lipoprotein fractions were shown to be associated in diabetes with and without complications ⁽¹⁰⁾. In the present study we found a significantly higher concentration of total cholesterol, TG, LDL-c, and lower HDL-c in patients with endothelial dysfunction. Non-HDL cholesterol serves as an index of cardiovascular risk in diabetic patients in whom LDL-c may not be elevated ⁽¹¹⁾. Studies have shown non-HDL-c being analogous to Apo B in assessing atherogenic cholesterol and lipoprotein burden ⁽¹²⁾. The apolipoprotein B assay is not routinely available because of its cost and general unfamiliarity with its interpretation outside of the research setting. Because of its simple calculation, the Non-HDL Cholesterol level is easily available with every lipid profile ordered and eliminating any additional costs ⁽¹³⁾. In a case-control study conducted with 60 angiographically confirmed patients and 60 healthy volunteers by Shilpa Bhardwaj et al found high Atherogenic Coefficient (AC), calculated as (non-HDL-c)/HDL-c) or (TC-HDL-c)/HDL-c) is a measure of cholesterol in LDL, VLDL, IDL fractions with respect to good cholesterol or HDL-c ⁽¹⁴⁾. The present study showed a significant increase levels of total cholesterol, triacylglyceride and lipid indices and their significant positive correlation with AIP in endothelial dysfunction (P<0.001).

Hence, AIP would be applied as an additional cardiovascular risk assessor even in the presence of insignificant changes in the individual lipids ⁽¹⁵⁾. In a study by Karbala et al also showed that AIP had highest sensitivity and specificity when compared with the other three atherogenic indices where its value of sensitivity was 84% versus 68%, 73%, and 76% for TC/HDL-c, HDL-c/LDL-c and LDL-c/HDL-c ratios ⁽¹⁶⁾. Dobiasova and Frohlich suggested that people with high AIP have a higher risk for coronary artery disease than those with low AIP and that AIP is positively correlated with the fractional esterification rate of HDL (FERHDL), and is inversely correlated with LDL particle size ⁽¹⁷⁾.  In view of this, calculating AIP can be more reliable in predicting the risk for development of atherosclerosis in patients of Endothelial dysfunction.

Lipid parameters along with AIP are found to have a good implication prospect in daily practice to assess cardiovascular risk in complications of endothelial dysfunction. These indices are calculated from the routinely done lipid profile parameters especially in centres where new tests are not possible due to cost factor. AIP is found to have better predictability to assess cardiovascular risk.

Conflict of Interest: Nil

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