Background: The hospital stay for "uncomplicated" acute myocardial infarction (AMI) is often too long. A reduction in the length of hospitalization, if proven to be safe, is advantageous in terms of costs and health organization. Accordingly the aims of the present, prospective study, were to evaluate: 1) the patients with AMI eligible for early discharge; 2) the incidence of adverse cardiovascular events within 2 weeks of myocardial infarction; 3) the incidence of cardiovascular mortality at 6-month follow-up.
Methods: On the fifth day after AMI, 331 of 526 patients, consecutively admitted to our coronary care unit between March 1997 and August 1999, were assigned to "complicated" and "uncomplicated" AMI groups, according to clinical and non-invasive criteria. Uncomplicated myocardial infarction eligible for early discharge was defined in patients < 75 years, as the absence of a high risk personality, stroke, left bundle branch block, transient myocardial ischemia after the first 24 hours from AMI, clinical signs or echocardiographic evidence of left ventricular dysfunction (ejection fraction < 40%), ventricular fibrillation, sustained ventricular tachycardia, symptomatic bradyarrhythmias after the first 48 hours from AMI, cardioversion or defibrillation (after the first 48 hours) or the need for coronary angioplasty or coronary artery bypass grafting. Uncomplicated patients were discharged on the sixth day after AMI (hospital stay 6.5+/-0.72 days). A symptom-limited ergometric stress test was planned in the uncomplicated group 14 days after AMI. "Hard" (death, reinfarction) and "non-hard" (unstable angina, myocardial revascularization) adverse cardiovascular events were monitored at 2 weeks of follow-up, and cardiovascular mortality at 6-month follow-up.
Results: Four (1.2%) hard (0.3% exitus and 0.9% reinfarction) and 7 (2.1%) non-hard adverse events occurred among patients with uncomplicated AMI at 2 weeks of follow-up. Patients with uncomplicated AMI who developed adverse events, presented during the primary coronary event creatine kinase (CK) and CK-MB serum levels which were significantly lower than those observed in patients who did not present adverse events. In the complicated group (hospital stay 9.9+/-1.79 days), from day 6 to 14 after AMI, 65 (33%) hard and non-hard events occurred. A significant reduction in mortality between the uncomplicated and complicated group (2.11 vs 27.17%, p < 0.0001) was observed at 6-month follow-up. Multivariate analysis showed a statistically significant difference for age and thrombolytic treatment.
Conclusions: This first Italian prospective study demonstrated the possibility of identifying, 5 days after AMI and on the basis of simple criteria and without a stress test, a low risk population of patients eligible for early discharge.