Associationofcoronaryatherosclerosiswith hyperapobetalipoproteinemia[increasedproteinbutnormal cholesterol levels in human plasma low density (β) lipoproteins]

Most patients with coronary artery disease do not have elevated plasma or low density lipoprotein (LDL) cholesterol.To test whether the protein moiety of LDL, LDL B, might be a parameter to identify ischemic heart disease, the plasma cholesterol, triglyceride, LDL cholesterol, and LDL B were measured in 100 consecutive patients undergoing cardiac catheterization. On the basis of coronary angiography, these patients were divided into two groups: group I, 31 patients without,and group I,59 patients with significant coronary artery disease. Although chlolesterol, triglyceride, and LDL cholesterol levels were al significantly higher in group I, discriminant analysis indicated that LDL B concentrations most clearly separated the two groups. In group I (noncoronary), LDL B was82± 22mg/100ml, whereas in group I, LDL B was 118 i 22 mg/100 ml. The B protein level in group I was similar to other normal groups studied (35 asymptomatic male physicians, 83± 11mg/100ml;90 normolipidemic medical students, 72i 17mg/100ml). The results therefore indicate that not only does LDL B better separate coronary and noncoronary groups than other lipid parameters studied, but also, among those with coronary artery disease, there exists a group with normal LDL cholesterol but with levels of LDL B protein similar to those observed in type I hyperlipoproteinemia. The explanation for the altered LDL composition observed in this group remains to be elucidated.