Serum Apolipoproteins a-I, a-Ii, B, C-Ii, C-Iii, E and Lipoprotein (A) in Angiographically Proven Coronary Artery Disease: An Indian Population Study

Background: Coronary artery disease (CAD) is the leading cause of death globally, with an accelerated rise among South Asians. Conventional lipid parameters explain only part of the risk, leaving many patients with “normal” lipid values but significant disease. Apolipoproteins, the protein components of lipoproteins, may serve as superior predictors of atherogenesis. Materials and Methods: We measured serum apolipoproteins A-I, A-II, B, C-II, C-III, E, and lipoprotein (a) [Lp(a)] in 121 angiographically proven CAD patients (76 diabetic, 45 non-diabetic) and 124 healthy controls. Standard lipid profiles were also assessed. Apolipoproteins were quantified by turbidimetric immunoassay Results: Apo A-I and A-II were significantly reduced in CAD patients compared to controls (p<0.001). Apo C-II was significantly elevated in diabetic CAD (p<0.001), while Lp(a) was consistently elevated in both diabetic and non-diabetic CAD groups (p<0.001). Apo B, C-III, and E showed no significant differences. Traditional lipid parameters revealed higher cholesterol, triglycerides, LDL-C, and VLDL-C with lower HDL-C in CAD. Conclusion: Reduced Apo A-I and A-II, together with elevated Apo C-II (in diabetic CAD) and Lp(a), are strongly associated with CAD in Indian patients. Apolipoproteins provide superior discriminatory value compared to traditional lipid measures. Establishing Indian-specific apolipoprotein reference intervals is crucial for accurate CAD risk assessment.