A Medical Research Study to Evaluate the Effects of ACT-246475 in Adults With Heart Attack

Main Inclusion Criteria: * Informed consent obtained prior to any study-mandated procedure, * Males aged from 18 to 85 and postmenopausal females aged up to 85 years, * Onset of symptoms of AMI of more than 30 min and less than 6 hours prior to randomization, * Subjects presenting a type I AMI including STEMI or NSTEMI. Main Exclusion Criteria: * Cardiogenic shock or severe hemodynamic instability, * Cardiopulmonary resuscitation, * Loading dose of any oral P2Y12 receptor antagonist prior to randomization, * Planned fibrinolytic therapy or any fibrinolytic therapy administered within 24 h prior to randomization, * Known platelet disorders (e.g., thromboasthenia, thrombocytopenia, von Willebrand disease). * Active internal bleeding, or bleeding diathesis or conditions associated with high risk of bleeding. * Known clinically important anemia. * Oral anticoagulation therapy within 7 days prior to randomization