Background: High lipoprotein(a) [Lp(a)] levels and small-sized apolipoprotein(a) [apo(a)] phenotypes have been linked to acute coronary syndromes (ACS). We sought to determine whether Lp(a) concentrations and apo(a) phenotypes may be related to the clinical syndrome of presentation among ACS patients.
Methods: Two hundred ten ACS patients and 105 controls were enrolled. One hundred thirteen patients presented with acute myocardial infarction (AMI) and 97 with unstable angina pectoris (UAP). Lp(a) concentrations were determined by ELISA and apo(a) isoforms were detected with a high-resolution immunoblotting method.
Results: Lp(a) levels and the percentage of subjects with at least one small-sized apo(a) isoform were significantly higher both in AMI patients and in UAP subjects as compared with controls. Among ACS patients, the percentage of subjects with at least one small apo(a) phenotype was significantly higher in patients who presented with AMI than in those with UAP (p<0.001). Multivariate logistic regression analysis showed that the presence of at least one small-sized apo(a) isoform was associated with AMI as the patient's clinical syndrome of presentation (OR=2.51, 95% CI: 1.38-4.58, p<0.01).
Conclusions: Among ACS patients, apo(a) isoforms of low molecular weight were associated with AMI onset. High-resolution apo(a) phenotyping might be helpful to identify individuals at high risk for developing AMI.