Effects of oxygen therapy on wall-motion score index in patients with ST elevation myocardial infarction-the randomized SOCCER trial

Background: Although oxygen (O₂) is routinely used in patients with acute myocardial infarction (AMI), it may have negative effects. In this substudy of the SOCCER trial, we aimed to evaluate the effects of O₂-treatment on myocardial function in patients with ST elevation myocardial infarction (STEMI). Methods: Normoxic (≥94%) STEMI patients were randomized in the ambulance to either supplemental O₂ or room air until the end of the percutaneous coronary intervention (PCI). The patients underwent echocardiography on day 2-3 after the PCI and once again after 6 months. The study endpoints were wall-motion score index (WMSI) and left ventricular ejection fraction (LVEF). Results: Forty-six patients in the O₂ group and 41 in the air group were included in the analysis. The index echocardiography showed no significant differences between the groups in WMSI (1.32±0.27 for O₂ group vs 1.28±0.28 for air group) or LVEF (47.0±8.5% vs 49.2±8.1%). Nor were there differences at 6 months in WMSI (1.16±0.25 vs 1.14±0.24) or LVEF (53.5±5.8% vs 53.5±6.9%). Conclusion: The present findings indicate no harm or benefit of supplemental O₂ on myocardial function in STEMI patients. Our results support that it is safe to withhold supplemental O₂ in normoxic STEMI patients.