RE-ACT is a national, multi-centre, observational, prospective, longitudinal cohort study which will include patients hospitalized for ACS within 24 hours of symptom onset and who have a final diagnosis of ST-segment elevation myocardial infarction (STEMI) or non-ST-segment elevation myocardial infarction (NSTEMI). This study aims to describe the short-term (at the end of the first month after index event) antithrombotic management patterns in a "real-life" setting for patients hospitalized with an acute coronary syndrome.