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

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.