OBJECTIVES: Randomized clinical trial comparing percutaneous coronary interventions (PCI) and non-invasive treatment acute coronary syndromes mostly favour the invasive approach. The aim of this study was to assess whether in a real life setting performing acute PCI would have an impact on outcomes as length of stay (LOS) and mortality in patients hospitalized for acute coronary syndromes in Belgium. METHODS: The average length of stay (LOS) and mortality among hospitalized patients with acute coronary syndrome were estimated using the longitudinal IMS Hospital Disease Database (year 2007), including data on 34.3% of Belgian hospital beds. Stays were identified based on ICD-9 coding and split in ST-elevated Myocardial infarction (STEMI ICD-9: 410 excluding 410.7), non-STEMI (ICD-9: 410.7-411.89) and unstable angina (ICD-9: 411.1-411.8-413.0). Invasive procedures were identified with ICD-9 codes corresponding to PCI (36.0). First stays in the calendar year were examined. Comparisons were performed using a Wilcoxon non-parametrical test for LOS and a Chi-square for mortality rates. RESULTS: In first hospitalizations, 3,420 STEMI, 2,070 non-STEMI and 954 unstable anginas were retrieved from the database, with respectively 1,206, 504 and 28 of them being treated invasively. LOS of patients undergoing PCI was significantly lower in STEMI (6.0 vs. 9.5 days; p<0.001) and non-STEMI (5.1 vs. 9.5; p<0.001). Mortality in patients with PCI was lower in both STEMI (3.5% vs. 17.2%; p<0.001) and non-STEMI (0.8% vs. 6.2%; p<0.001). Although LOS and mortality in non-invasively treated patients were lower in hospitals without a cathlab compared to hospitals with a cathlab, both parameters were significantly higher compared to PCI treated patients. CONCLUSIONS: Although information on the baseline characteristics of the different patients is limited, the findings of this observational study seem to support randomized clinical trials. Treatment with PCI decreases the LOS and the mortality significantly in patients with a myocardial infarction.