Comparison of fasting and postprandial plasma lipoproteins in subjects with and without coronary heart disease

Plasma lipoprotein levels, including remnant-like particle (RLP) cholesterol and RLP triglycerides, were assessed in fasting (12 hours) and postprandial (PP) (4 hours after a fat-rich meal) states in 88 patients with coronary heart disease (CHD) and 88 controls. All lipoproteins were assessed by direct methods. We hypothesized that patients with CHD would have greater percent increases in their triglyceride levels, RLP cholesterol, and RLP triglycerides, in response to a fat-rich meal. In the fasting state, triglycerides, RLP cholesterol, RLP triglycerides, and low-density lipoprotein (LDL) cholesterol levels were all significantly higher in cases versus controls by 51%, 35%, 39%, and 40%, respectively. These levels were 57%, 37%, 64%, and 37% higher in the PP state, respectively. Mean high-density lipoprotein (HDL) cholesterol values were 27% lower in cases in both the fasting and PP states. After eating, triglycerides, RLP cholesterol, and RLP triglycerides increased 64%, 71%, and 290% in controls, respectively, whereas in cases these levels increased by 71%, 94%, and 340%, respectively (all p <0.0001). Percent increases in the PP state were not significantly different in cases versus controls. Following the fat-rich meal, LDL and HDL cholesterol decreased by 5% and 4% in controls, and by 7% and 6% in patients, with no significant difference in percent changes between groups. Fasting values correlated very highly with PP values for all parameters (all p <0.0001). Our data indicate that although patients with CHD have higher fasting and PP levels of triglycerides, RLP cholesterol, and RLP triglycerides than controls, the response (percent increase) to a fat-rich meal is comparable in both groups. Thus, a feeding challenge is not essential for assessment of these lipoproteins. Moreover, it is not necessary to obtain a fasting sample to assess direct LDL and HDL cholesterol.