Background Although cardiogenic shock (CS) is the leading cause of death for acute myocardial infarction (AMI) patients, reliable predictive factors in the acute stage, such as cardiovascular peptides, have not yet been identified. Methods and Results In 42 consecutive AMI patients with CS on admission, successfully treated by primary percutaneous coronary intervention (PCI) within 12 h of onset, related factors including brain natriuretic peptide (BNP), atrial natriuretic peptide (ANP), renin, aldosterone, catecholamines, and adrenomedullin, were investigated 24 h from onset, as well as the 1-year mortality rates. During the 12-month follow-up period, 15 patients died from cardiovascular causes (group D). There were no significant differences in patient characteristics, angiographic findings, and left ventricular systolic function between group D subjects and the survivors (group S: n=27). Multivariate analysis identified high levels of adrenomedullin as an independent predictor of 1-year mortality (risk ratio: 6.42, 95% confidence interval, 1.49-43.31, p<0.05). Conclusions The acute-phase plasma concentration of adrenomedullin may be a reliable predictor of mortality in patients with AMI complicated by CS and successfully treated by direct PCI, as may be BNP concentration, peak-creatine kinase value, and ventricular fibrillation. (Circ J 2005; 69: 83 - 88)