Apolipoprotein(a) phenotypes predict the severity of coronary artery stenosis

Abstract

Background: Studies on the impact of elevated levels of lipoprotein(a) (Lp[a]) or apolipoprotein(a) (apo[a]) on the development of coronary artery disease have given controversial results. The relationship between apo(a) phenotypes and coronary artery stenosis remains unclear.

Methods: Lipid profiles, and apo(a) levels and phenotypes were analyzed in 225 patients who underwent elective coronary angiography. Coronary artery stenosis, as indicated by angiography, was estimated by a newly devised minimal lesion (ML) grading system. Relationships between lipoprotein variables and coronary artery stenosis were examined by linear and logistic regression models.

Results: On the basis of ML score, patients with larger apo(a) phenotypes (S3, S3a or S4) had a lower rate of coronary artery stenosis (68%-76%) than those with smaller phenotypes (S1, S1a, S2 or S2a - 79%-95%). The odds of coronary artery stenosis in patients with smaller apo(a) phenotypes were significantly different from those of patients with larger phenotypes (p < 0.001). Also, patients with a history of myocardial infarction, angina, hypertension, diabetes or hypercholesterolemia were more likely to show coronary artery stenosis on angiography. With respect to lipid levels, 20.2% of patients had an elevated serum total cholesterol (TC) level and 16.1% an elevated low-density lipoprotein cholesterol (LDL-c) level. In 21.3%, the high-density lipoprotein cholesterol (HDL-c) level was decreased. There were significant positive correlations of serum TC with those of the TC/HDL-c ratio, LDL-c, triglycerides and HDL-c (p < 0.05 and 0.001), of LDL-c with TC and apo(a) (p < 0.001) and of ML scores with the TC/HDL-c ratio and patient age (p < 0.01 and 0.001). There were significant negative correlations of TC and apo(a) levels with apo(a) phenotypes (p < 0.05 and 0.001) and of ML scores with HDL-c (p < 0.001). The odds of coronary artery stenosis in patients with abnormally high apo(a) levels (44.6%) were not significantly different from those of patients with apo(a) levels in the normal range.

Interpretation: Smaller apo(a) phenotypes, but not elevated levels of apo(a), may help to predict the rate and severity of coronary artery stenosis. HDL-c independently and negatively correlated with the extent of the stenosis.