Background : Occlusive coronary artery spasm can induce acute myocardial infarction (AMI). The purpose of this study is to determine the risk factors for the development of AMI in patients with coronary vasospasm. Methods : Consecutive 231 patients documented coronary vasospasm by ergonovine provocation test were devided into two patient groups, angina pectoris (group I: n=202, 49.5짹11.5 years) and acute myocardial infarction (group II: n=29, 47.4짹11.2 years). Results : Baseline clinical characteristics were not different between the two groups. The levels of lipoprotein(a) [Lp(a)], fibrinogen, high sensitivity C-reactive protein (hsCRP), apolipoprotein B/A1 ratio were measured. The levels of hsCRP and fibrinogen were higher in group II (1.88짹2.9 mg/dL, 317.5짹51.2 mg/dL) than in group I (0.68짹1.5 mg/dL, 263.2짹70.3 mg/dL; p<0.001, p=0.002 respectively). The level of fibrinogen higher than 300 mg/dL is an independent determinant for the AMI due to occlusive vasospasm according to multivariate analysis (OR=7.13, 95% CI=2.16 to 23.54, p=0.001). Conclusions : Elevated levels of fibrinogen is associated with AMI due to occlusive coronary spasm, suggesting that fibrinogen may play important role in the genesis of thrombotic coronary occlusion subsequent to coronary spasm.