Objectives: The purpose of this study is to determine whether lipoprotein(a) (Lp[a]) is an independent risk factor for coronary spasm and occurrence of acute myocardial infarction (AMI) in patients with coronary spasm.
Background: Although elevated serum Lp(a) levels are known to be associated with coronary atherosclerosis and AMI, the association between the elevated level of this lipoprotein and coronary spasm remains to be elucidated.
Methods: Serum Lp(a) levels were measured using a latex immunoassay in 77 patients with coronary spasm but without a significant (>75%) fixed coronary stenosis, including 16 with prior myocardial infarction (MI), in 177 patients with a fixed stenosis but without rest angina, including 114 with prior MI and in 81 control subjects without coronary artery disease.
Results: The serum Lp(a) level in patients with coronary spasm (median; 17 mg/dl) was higher (p < 0.01) than in control subjects (12 mg/dl) but lower (p < 0.01) than in patients with a fixed stenosis (23 mg/dl). The incidence of subjects with higher (>25 mg/dl) serum Lp(a) levels was higher in patients with a fixed stenosis (46%, p < 0.01) but not in patients with coronary spasm (27%), compared with control subjects (21%). Among the patients with coronary spasm, the incidence of higher Lp(a) levels was higher in patients with than in those without a history of prior MI (56% vs. 21%, p < 0.05). The patients with higher Lp(a) levels had a higher incidence of prior MI than those without (41% vs. 13%, p < 0.05). The multivariate analysis confirmed that higher serum Lp(a) level is an independent determinant for prior MI in these patients (odds ratio, 4.19; 95%, confidence interval, 1.03 to 17.00).
Conclusions: Elevated serum level of Lp(a) was found to be associated with a history of prior MI in patients with coronary spasm, suggesting that Lp(a) may play an important role in the genesis of thrombotic coronary occlusion and the occurrence of AMI subsequent to coronary spasm.