CLINICAL STUDIES
Lipoprotein(a) is a risk factor for occurrence of acute myocardial infarction in patients with coronary vasospasm
Kunihisa Miwa, MDa,
Keiko Nakagawa, MDa,
Naohiro Yoshida, MDa,
Yoshiharu Taguchi, MDa and
Hiroshi Inoue, MD, FACCa
a The Second Department of Internal Medicine, Toyama Medical and Pharmaceutical University, Toyama, Japan
Manuscript received October 21, 1998;
revised manuscript received November 9, 1999,
accepted December 29, 1999.
Reprint requests and correspondence: Dr. Kunihisa Miwa, The Second Department of Internal Medicine, Kansai Electric Power Hospital, 2-1-7 Fukushima, Fukushima-ku, Osaka 553-0003, Japan
k-21568{at}kepco.co.jp
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.
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Abbreviations and Acronyms
| | AMI | = acute myocardial infarction | | apo(a) | = apolipoprotein(a) | | HDL | = high-density lipoprotein | | LDL | = low-density lipoprotein | | Lp(a) | = lipoprotein(a) | | MI | = myocardial infarction | | PAI | = plasminogen activator inhibitor | | t-PA | = tissue-type plasminogen activator |
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