 In an ongoing register randomized multicentre clinical trial, the DETO2X Determination of role of oxygen in suspected acute myocardial infarction study, the effect of oxygen on morbidity and mortality in ACS patients is being investigated. In a substudy of the DETO2X-trial, the investigators have planned to evaluate the effect of oxygen treatment on IR-injury in STE-ACS as assessed by biomarkers reflecting various aspects of the pathological processes involved. 