Serum small dense low-density lipoprotein (sd-LDL) concentrations were measured in patients with angiographically defined coronary artery disease (CAD) and compared to concentrations in healthy subjects. Five hundred and seventy patients with stable CAD were divided into CAD- and CAD+ based on angiography. Patients in whom stenosis was <50 % in diameter were classified as having a 'normal' angiogram (CAD-), otherwise the patients were allocated to the CAD+ group. The CAD+ group was further subcategorized into single-, double- and triple-vessel disease (VD). Serum sd-LDL concentrations were significantly lower in controls compared with CAD+ and CAD- patients (P < 0.001). Moreover, CAD+ patients had higher concentrations of sd-LDL than CAD- patients (P < 0.01). sd-LDL levels were not significantly associated with severity of CAD defined by the number of stenosed coronary arteries (P = 0.245). All participants were also categorized into subgroups with or without metabolic syndrome. Subjects with metabolic syndrome had higher levels of sd-LDL than subjects without metabolic syndrome (P < 0.01). Multiple linear regressions showed that in CAD patients, triacylglycerol, total-cholesterol, body mass index, and waist circumferences were the most important determinants of serum sd-LDL concentrations. We found that sd-LDL levels were significantly higher in patients presenting with symptoms of CAD. Moreover, patients with significant stenosis of their coronary arteries (>50 % stenosis) had higher levels of sd-LDL compared to patients without significant lesions.

This study aimed at evaluating the serum High‐density lipoprotein lipid peroxidation (HDLox) levels and their association with coronary artery disease (CAD). This case–control study comprised 572 patients with stable CAD and 281 healthy subjects with no history of cardiovascular disease (control group). Based on the results of coronary angiography, the patient group was divided into two groups: CAD− and CAD+. HDLox was measured using a fluorimetric method. The ability of HDLox and serum high‐density lipoprotein cholesterol (HDL‐C) to detect CAD and coronary artery stenosis ≥50% was also compared using the receiver operating characteristic (ROC) curve analysis. The CAD patients showed significantly higher serum HDLox levels, compared to the control group [1.15 (1.01–1.31) vs. 0.85 (0.62–1.06), no units, p < 0.001]. Moreover, serum HDLox levels were significantly lower in CAD− patients, compared to the CAD+ patients [1.05 (0.92–1.22) vs. 1.24 (1.12–1.35), no units, p < 0.001]. According to the results of univariate and multivariate logistic regression, the HDLox showed association with the presence of CAD (odds ratio [OR]: 1.754; 95% confidence interval [CI]: 1.564–1.968; p < 0.001) and coronary artery stenosis ≥50% (OR: 1.729; 95% CI: 1.534–1.949; p < 0.001). The results obtained from the area under the ROC curve revealed that the HDLox could better detect the risk of CAD and coronary artery stenosis ≥50% compared to serum HDL‐C level. The oxidation of HDL leads to a reduction in its antioxidant function and it has a crucial role in the development of atherosclerosis. HDLox is suggested as a diagnostics biomarker for CAD.