There is a lack of consensus among cardiologists regarding the length of time patients should be hospitalized after an uncomplicated acute myocardial infarction (AMI) and successful direct percutaneous coronary intervention (d-PCI). The purpose of this study was to evaluate the feasibility and safety of early discharge (discharge <4 days after the procedure) for low risk patients with AMI who underwent successful d-PCI. From May 1996 through December 2001, d-PCI was performed in 898 consecutive patients with AMI. Of these 898 patients, 463 (51.6%) were stratified to be at low risk. Lower risk was defined as: (1) Killip classification < or = 2 on admission; (2) the infarct-related artery achieved normal blood flow without recurrent ischemia or reinfarction in the first 24 hours; (3) no mechanical or electrical complications after d-PCI. (4) no acute renal failure, acute stroke, or major bleeding complication; (5) no advanced congestive heart failure (defined as > or = New York Heart Association functional class 3); and (6) no sepsis. Patients who were discharged <4 days after undergoing the procedure were enrolled in group 1 (n = 266). Patients who were discharged > or = 4 days after undergoing the procedure were enrolled in group 2 (n = 197). Univariate analysis demonstrated that group 2 patients had a significantly longer hospital stay (P = 0.0001) than group 1 patients. At the first 30-day follow-up examination, there were no significant differences in the combined major cardiac events (death, recurrent isehemia, reinfarction, revascularization. or advanced congestive heart failure) between the group 1 and group 2 patients (1.50% vs 1.52%, P = 0.92). There were also no significant differences in the combined major noncardiac complications (acute stroke, acute renal failure, bleeding complications requiring blood transfusion, vascular sequelae, or sepsis) between the group 1 and group 2 patients (1.13% vs 0.51%. P = 0.89). Early discharge was feasible in a majority of the patients who experienced AMI and were at lower risk 24 hours after successful d-PCI. Thus, the patients had a shortened hospital stay and no increased risk.