BACKGROUND AND OBJECTIVES: It has been known that myocardial ischemia augments the synthesis and release of B-type natriuretic peptide (BNP). Although plasma BNP has been shown to provide prognostic information in patients with left ventricular (LV) dysfunction after acute myocardial infarction (AMI), limited data are available for the patients with preserved LV systolic function. We investigated 6-month prognostic value of plasma N-terminal pro-BNP (NT-proBNP) in patients with preserved LV systolic function (LV ejection fraction (EF) >50%) following AMI. METHODS: Between November 2005 and January 2008, 3264 eligible patients (2330 males and 934 females; mean age=62.9 짹 0.2 year-old) were analyzed in the Korea Acute Myocardial Infarction Registry (KAMIR). We excluded patients with renal dysfunction (serum creatinine >1.5mg/dL) RESULTS: Six-month mortality was 1.5% in patients with preserved LV systolic function after index AMI. In multivariate logistic regression analysis, log-transformed NT-proBNP (odds ratio [OR] 1.39, 95% confidence interval [CI] 1.01 to 1.91, p=0.045), previous ischemic heart disease (OR 3.03, 95% CI 1.12 to 8.15, p=0.029), anti-platelet drugs (OR 0.04, 95% CI 0.01 to 0.32), systolic blood pressure (OR 0.98, 95% CI 0.97 to 0.99) were independent predictors of 6-month mortality after adjustment for confounding variables. Receiver operating characteristic (ROC) curve showed a best cut/off value of NT-proBNP to predict 6-month mortality was 943.5pg/mL with a sensitivity of 61.2% and a specificity of 77.1% (AUC = 0.710, p <0.001). Conclusions: Plasma NT-proBNP is an independent predictor of 6-month mortality in post-MI patients with preserved LV systolic function.