Serum small dense low-density lipoprotein concentrations are elevated in patients with significant coronary artery stenosis and are related to features of the metabolic syndrome.

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.