Background:According to Multicenter Automatic Defibrillator Implantation Trial (MADIT)II criteria, post MI patients whose left ventricular ejection fraction(LVEF) lower than 30%(high risk for sudden cardiac death(SCD)) indicated for ICD implantation. Other non-invasive parameters derived from Holter and signal-averaged ECG(SAECG) are known to have predictive value for SCD risk. However, data about prevalence of SCD risk factors and associated mortality rate of Kore-an post MI patients are lacking in the era of prophylactic ICD implantation for primary prevention of SCD. Objectives:The aim of study is to reveal the inciden-ce and the prognostic value of noninvasive parameters and whether MADIT II crit-eria for ICD implantation is appropriate in Korean PMI patients. Methods:During the period 2001 to 2005, 640 PMI survivors underwent echocardiography, Holter ECG and SAECG before discharge were selected. The incidence of abnormal SAECG, premature ventricular complex(PVC) counts>10/hr, non-sustained VT and VT on Holter ECG, and low(���30%) LVEF were studied and used as risk stratification markers for later adverse arrhythmic events defined as VT, ventricular fibrillation and/or SCD. Results:The incidence of PVCs>10/hr was 13.6%(73/535), and NSVT or VT on Holter ECG was 7.3%(39/535).39 of 272(14.3%)had late potential on SAECG. Patients who have LVEF less than 30% were 4.4%(25/571). The SCD or adverse arrhythmic events were occurred in 5.9%(38/640)during 20.9짹16.1 months of mean follow-up. Of 73 patients with PVCs>10/hr, 14 patients(19.2%); and of 39 patients with NSVT/VT episodes, 6 patients(19.2%)suffered from arrhythmic events(p<0.05). Arrhythmic events were occurred in 9 (31.0%) among 29 patients with lower LVEF(p<0.05). Of 29 patients with MADIT II characteristics, 8 patients(27.6%) died, which was larger than that of conventi-nal therapy group of MADIT II study despite similar age and LV function. The presence of late potential did not predict the events.Conclusion: Frequent PVCs(>10/hr) and LVEF less than 30% have a significant prognostic value for SCD risk stratification. MADIT II criteria and abnormal Holter ECG findings can be suggested as an indication for implanting ICD in Korean PMI patients.