Lack of association between plasma lipoprotein(a) concentrations and the presence or absence of coronary atherosclerosis

Background - Findings from previous studies relating lipoprotein(a) [Lp(a)] as an independent risk factor for coronary atherosclerosis and the presence of angiographically detectable coronary atherosclerotic lesions are not consistent. This study was performed to determine whether the plasma concentration of Lp(a) is associated with coronary atherosclerosis asessed by coronary angiography. Methods - We studied a total of 100 men and women (41 women, 59 men, age 63.7+/- 11.0 years) who were referred for coronary angiography. Base-line data collection comprised conventional risk factors for coronary artery disease, lipids, fasting total homocysteine, and clinical characteristics. The relation between plasma Lp(a) levels and the presence or absence of coronary lesions was studied. The coronary angiograms were evaluated in a blinded manner. Any coronary stenosis was considered as coronary artery disease (CAD). Results - From the 100 patients, 40 were found to have no CAD and 60 had CAD assessed by coronary angiography. Estimates of the relative risk of coronary heart disease for the fifth quintile of plasma Lp(a) as compared with the first quintile were 0.87 (95 percent confidence interval, 0.66 to 1.34). After adjustment for age, sex, lipoproteins, and homocysteine levels, estimates of the relative risk of coronary heart disease for the fifth quintile of plasma Lp(a) as compared with the first quintile were 1.06 (95 percent confidence interval, 0.81 to 1.39). The presence of angiographic CAD was associated with patient age (p = 0.048), male sex (p<0.01), high LDL-cholesterol levels (p=0.02), low HDL-cholesterol levels (p=0.02), high plasma fibrinogen levels (p<0.01) and high fasting total homocysteine levels (p=0.04). Conclusion - These results suggest that the plasma concentration of Lp(a) is not associated with the presence of coronary artery disease in patients referred for coronary angiography.