High Lipoprotein(a) Levels are Associated With Long-Term Adverse Outcomes in Acute Myocardial Infarction Patients in High Killip Classes

BACKGROUND AND OBJECTIVES: An elevated concentration of lipoprotein(a) {Lp(a)} is associated with an increased prevalence and increased severity of coronary artery disease. However, the relationship between Lp(a) levels and outcomes after acute myocardial infarction (AMI) is unclear. SUBJECTS AND METHODS: Between October 2005 and June 2007, we measured serum Lp(a) levels in 832 consecutive AMI patients (age, 62.8±12.4 years, 600 men) on admission. They were divided into tertiles according to their serum Lp(a) levels {Tertile 1 (n=276), Lp(a)<13.8 mg/dL; Tertile 2 (n=279), Lp(a)=13.8-30.6 mg/dL; Tertile 3 (n=277), Lp(a)>30.6 mg/dL}. RESULTS: There were no differences in baseline clinical characteristics among Tertiles 1, 2, and 3, except for proportions of Killip class III-IV patients (5.8% vs. 10.0% vs. 18.8%, respectively, p<0.001). There were significant differences in left ventricular ejection fractions (57.3±11.4% vs. 55.9±12.3% vs. 53.1±13.1%, p<0.001). Among the laboratory findings, there were significant differences in total cholesterol (173.3±37.2 vs. 183.5±38.9 vs. 185.3±43.8 mg/dL, p=0.001), low density lipoprotein-cholesterol (111.3±34.3 vs. 122.9±34.7 vs. 123.3±39.4 mg/dL, p<0.001), apolipoprotein B (92.8±25.4 vs. 100.8±26.0 vs. 101.9±28.8 mg/dL, p<0.001), and amino-terminal pro-brain natriuretic peptide levels (1805.2±4343.3 vs. 2607.9±5216.3 vs. 3981.5±7689.7 pg/mL, p<0.001). After adjusting for multiple variables in the high Killip class (III-IV) subgroup, the risk estimate for major adverse cardiovascular events (MACE) at 1-year follow-up was significantly higher in Tertile 3 than in Tertiles 1 or 2 (hazard ratio 6.723, 95% confidence interval 1.037-43.593, p=0.046). CONCLUSION: In patients in high Killip classes, high serum levels of Lp(a) were significantly associated with long-term adverse outcomes after AMI.