Lipoprotein(a) in coronary heart disease: a case-control study

To determine the significance of lipoprotein(a) levels in coronary heart disease patients, a case-control study was performed with 48 newly diagnosed coronary heart disease patients and 23 controls who were evaluated using clinical history and biochemical examination. Lipoprotein(a) was measured by quantitative latex-enhanced immunoturbidimetric method. Geometric means of biochemical parameters were obtained. Comprehensive lipid tetrad index was calculated using a previously validated formula. There was no significant difference in prevalence of diabetes, hypertension and smoking in cases and controls. Dietary intake of calories, fats, fatty acids and antioxidant vitamins was also similar. The levels of fasting glucose, cholesterol, low-density lipoprotein cholesterol, high-density lipoprotein cholesterol and triglycerides were not significantly different in cases and controls (p > 0.05). Low-density lipoprotein/high-density lipoprotein ratio (4.33 +/- 1.5 vs 4.29 +/- 1.8) and total cholesterol/high-density lipoprotein ratio (6.59 + 1.7 vs 6.69 +/- 2.2) were similar. The mean lipoprotein(a) levels were significantly greater in cases (11.95 +/- 2.8 mg/dL, range 1-102 mg/dL) as compared to controls (6.68 +/- 3.4 mg/dL, range 1-73 mg/dL) (t = 2.08, p = 0.041). As compared to controls, in coronary heart disease cases, mean lipoprotein(a) levels in patients upto 50 years (10.27 +/- 2.8 vs 7.27 +/- 3.4 mg/dL) as well as those over 50 years (12.99 +/- 2.9 vs 4.91 +/- 3.5 mg/dL) were significantly more (p < 0.05). Coronary heart disease patients had a slightly greater prevalence of high lipoprotein(a) levels, 20 mg/dL or more (31.3 vs 13.0%; chi 2 = 2.83, l-tailed p < 0.05). Comprehensive lipid tetrad index (total cholesterol x triglycerides x lipoprotein(a) divided by high-density lipoprotein cholesterol) was also slightly higher in cases (14688.2 +/- 3.6) than in controls (8358.2 +/- 4.3) (t = 1.68, 1-tailed p < 0.05). This study shows that lipoprotein(a) levels are significantly more in both younger and older coronary heart disease patients as compared to controls.