Significance of small dense low-density lipoproteins and other risk factors in patients with various types of coronary heart disease

Background It remains unclear how closely the small dense low-density lipoprotein (LDL)(diameter less than or equal to25.5nm) is associated with various types of coronary heart disease (CHID) in Japanese patients, an ethnic group with lower serum cholesterol levels and less massive obesity compared with Western populations. Methods and Results We measured mean LDL particle diameter by gradient gel electrophoresis in 571 patients with CHID and in 263 healthy subjects who served as control patients. Patients with CHID were classified into acute coronary syndrome (ACS), stable CHD and vasospastic angina. High-density lipoprotein cholesterol and apolipoprotein-A1 and -B were significantly different between patients with CHID and controls. LDL size in patients with CHID was markedly smaller than that in controls in both men and women (25.5 +/- 0.7 vs 25.9 +/- 0.4 and 25.7 +/- 0.7 vs 26.0 +/- 0.5 nm, respectively). LDL cholesterol was significantly higher in patients with ACS than in other groups. Plasma levels of high-clensity lipoprotein cholesterol decreased as the number of diseased vessels or angiographic coronary severity evaluated by Gensini score increased, but the LDL size was comparable irrespective of the type of CHID and the extent and severity of the lesions. Multiple logistic regression analysis revealed that small dense LDL was independently associated with the incidence of CHID in both sexes (odds ratio [OR] 3.5, 95% CI 2.1-5.7, and OR 2.9, 95% CL 1.5-5.6, P <.005). Conclusion Our study suggests that the small dense LDL is strongly associated with various types of CHID, independent of traditional and nontraditional coronary risk factors, but is not related to the severity and extent of the coronary lesions.