Triglyceride enriched lipoprotein particles correlate with the severity of coronary artery disease

A group of 100 male normotensive, non-obese, non-diabetic subjects who had undergone coronary angiography were studied to determine relationship between the severity of coronary artery disease (CAD) and plasma lipids, apolipoproteins and lipoprotein particles defined by their apolipoprotein composition. CAD was found in 84 and no measurable lesions were found in 26 subjects. The severity of CAD was determined on the basis of size and number of lesions and expressed in terms of a global CAD score. Low density lipoprotein (LDL)-cholesterol showed a tendency to be higher in CAD patients than in CAD-free subjects (216 vs. 205 mg/dl, P = 0.07). HDL-cholesterol showed a tendency towards lower values in CAD patients compared to CAD-free subjects 35 vs. 41 mg/dl, P = 0.07). In univariate analysis the severity of CAD correlated with (i) complex, apolipoprotein (apo) B containing particles (Lp-B-complex, r = 0.31, P = 0.005), (ii) HDL-cholesterol (r = -0.30, P = 0.005), (iii) apoC-III in heparin precipitate (r = 0.30, P = 0.005) and (iv) plasma triglycerides (r = 0.25, P = 0.02), all of which are related to triglyceride-rich lipoproteins. A comparison between the two subspecies of complex lipoprotein particles revealed that those containing apolipoproteins B, C-III and E (Lp-B:C:E complex) were more closely associated with CAD score (r = 0.27, P = 0.01) than those containing apolipoproteins A-II, B, C, D and E (Lp-A-II:B-complex). LDL-cholesterol also correlated with the global CAD score (r = 0.23, P = 0.03). In multiple regression analysis only HDL-cholesterol (P = 0.003), apoC-III-ratio (P = 0.007), Lp-B-complex (P = 0.02) and Lp-B:C:E-complex (P = 0.04) showed significant correlation with CAD score. The results of this study demonstrate that some of the triglyceride rich lipoprotein particles represent a risk factor for CAD and support the clinical usefulness of specific assays capable of distinguishing lipoprotein particles on the basis of apolipoprotein composition.