Background and Objectives:Heart failure is a progressive chronic disease with high morbidity and mortality.The aim of this study was to determine whether the N-terminal pro B-type natriuretic peptide (NT-proBNP)levels in the blood can predict readmission due to heart failure or cardiac death (cardiac event) following hospitaldischarge, and if these are a better predictive marker than a pre-discharge echocardiogram or other laboratoryparameters in discharged patients with idiopathic dilated cardiomyopathy (DCM). Subjects and Methods:Theoutcomes of 36 patients with idiopathic DCM, diagnosed on hospital admission, were retrospectively evaluated.Results:During a mean follow-up period of 520 days, a 22.2% rate of cardiac events was observed. Evaluationof the NT-proBNPs showed the mid-term (mean 84th day after discharge) outpatient (OPD) NT-proBNP levelsto be a strong predictor of cardiac events, with an area under the curve analysis of 0.90. The optimal mid-termOPD NT-proBNP cut-off level for predicting cardiac events was 1500 pg/mL, with a sensitivity and specificity of80 and 92%, respectively; patients with levels above this threshold had a 22.9 hazard ratio for cardiac eventscompared to those with levels below this threshold. Conclusion:The mid-term OPD plasma NT-proBNP levelswere able to predict cardiac events in discharged patients with idiopathic DCM, regardless of the admission or predischargeNT-proBNP levels and other laboratory parameters. The measurement of OPD NT-proBNP at themid term follow-up may be useful in outpatient therapeutic monitoring or for the development of prognosticguidelines in patients with idiopathic DCM. (Korean Circulation J 2007;37:202-207)