Identification of acute myocardial infarction patients suitable for early hospital discharge after aggressive interventional therapy. Results from the Thrombolysis and Angioplasty in Acute Myocardial Infarction Registry. BACKGROUND. Very early (day 4) hospital discharge has recently been proposed for selected patients with acute myocardial infarction (MI). The purpose of this study was to determine the most useful factors for identifying acute MI patients treated with aggressive interventional therapy who could be safely discharged on day 4. METHODS AND RESULTS. We studied 708 patients enrolled in the Thrombolysis and Angioplasty in Acute Myocardial Infarction trials I-III. Patients dying in the first 3 days and those with early (days 1-3) emergency coronary artery bypass graft surgery (CABG), late elective CABG (greater than or equal to day 4), or urgent/emergency CABG resulting from a late elective coronary angioplasty were excluded. The remaining 580 patients were randomly divided into a training sample (group 1) that was used to build a logistic regression model for predicting the absence of a late major complication and a test sample (group 2) that was used to validate this model. For this study, patients were considered appropriate for day 4 hospital discharge if they did not experience any of the following for 30 days after MI: death, reinfarction, cardiogenic shock, pulmonary edema, sustained hypotension, sustained ventricular tachycardia, high-grade atrioventricular block, acute ventricular septal defect, and recurrent ischemia necessitating urgent CABG. In group 1, four variables were independent predictors of freedom from late major complications: absence of early sustained ventricular tachycardia or ventricular fibrillation, absence of early sustained hypotension or cardiogenic shock, fewer coronary arteries with significant (greater than or equal to 75%) stenosis, and a higher left ventricular ejection fraction. In group 2, 23% of patients had a logistic model prediction of a 3% or less chance of a late complication. These patients had no deaths or reinfarctions by day 30 and a 3% late major complication rate. CONCLUSIONS. The results of early cardiac catheterization and the absence of selected early (days 1-3) major complications do allow identification of a low risk subgroup of acute MI patients that may be suitable for very early discharge. 