Comparison of apolipoprotein B to cholesterol in low density lipoproteins of patients with coronary heart disease.

This study was carried out to determine whether patients with coronary heart disease (CHD) have an unusually high level of apolipoprotein B (apoB) relative to cholesterol (C) in low density lipoproteins (LDL). Seven groups of men were studied. Seventy-two with normolipidemia (NLP) had CHD documented on clinical grounds; another 34 NLP patients had proven coronary artery disease (CAD) by angiography (greater than 50% occlusion of two or three coronary arteries). Another group of 37 with documented CHD had hypertriglyceridemia (HTG), and still another 25 with HTG had proven CAD. Three normolipidemic control groups consisted of 30 healthy young men, 40 healthy middle-aged men, and 35 hypertensive men. In normolipidemic CHD and CAD patients, plasma LDL-C averaged 142 +/- 37 (SD) and 136 +/- 32 mg/dl, respectively; in HTG patients with CHD and CAD, LDL-C levels were 137 +/- 37 and 127 +/- 34 mg/dl, respectively. These values were near those of hypertensive controls (141 +/- 31 mg/dl), but higher than middle-aged and younger healthy controls (118 +/- 32 and 106 +/- 26 mg/dl, respectively). Levels of LDL-apoB followed a similar pattern: CHD-NLP (88 +/- 25 mg/dl), CAD-NLP (83 +/- 25 mg/dl), CHD-HTG (94 +/- 30 mg/dl), CAD-HTG (89 +/- 25 mg/dl), hypertensive controls (89 +/- 24 mg/dl), middle-aged controls (80 +/- 25 mg/dl) and younger controls (58 +/- 14 mg/dl). Normolipidemic patients with CHD and CAD did not have higher LDL-C and LDL-apoB levels than hypertensive and normotensive controls. HTG patients with CHD and CAD however tended to have higher LDL-apoB levels, and their LDL-apoB/C ratios were higher on average than normal. Nevertheless, among all coronary groups, there were no sizable subgroups with elevated LDL-apoB; only about 11% of all coronary patients had LDL-apoB levels over 120 mg/dl (compared to 8% for normo- and hypertensive controls of middle age). The data of this study therefore suggest that LDL-apoB may not prove to be a better indicator of coronary risk in normolipidemic people, but LDL-apoB could be a superior predictor of risk in HTG patients.