['An evaluation of the relation between small dense low-density lipoprotein cholesterol (sd-LDL-C) levels measured by the heparin-magnesium precipitation method and metabolic syndrome (MetS).', 'We have prospectively measured sd-LDL-C levels by the heparin-magnesium precipitation method in 112 Japanese patients (male/female=80/32) with coronary artery disease (CAD) who received percutaneous coronary intervention (PCI). Patients were diagnosed with MetS according to modified Japanese criteria.', 'A total of 36 patients (32%) met the criteria for MetS. Sd-LDL-C levels were significantly higher in the MetS group than non-MetS group (20.7 +/- 1.5 mg/dL vs. 17.1 +/- 1.0 mg/dL, p=0.042), especially among patients without lipid-lowering therapy (26.4 +/- 2.6 mg/dL vs. 17.5 +/- 1.5 mg/dL, p= 0.0034). Sd-LDL-C levels gradually increased with the number of components used to define MetS (0; 14.5 +/- 1.8 mg/dL, 1; 16.5 +/- 1.8 mg/dL, 2; 16.7 +/- 1.3 mg/dL, 3; 19.3 +/- 1.7 mg/dL, 4; 23.1 +/- 2.1 mg/dL, 5; 40.0 mg/dL, p=0.0071). High-sensitivity C-reactive protein (hs-CRP) levels were significantly higher in the patients with MetS (1.09 +/- 0.17 mg/L vs. 0.67 +/- 0.09 mg/L, p=0.0204).'] Is small dense low-density lipoprotein cholesterol a useful marker of metabolic syndrome in patients with coronary artery disease?