Prehospital opioid dose and myocardial injury in patients with ST elevation myocardial infarction

OBJECTIVE: To characterise the relationship between opioid dose and myocardial infarct size in patients with ST elevation myocardial infarction (STEMI). METHODS: Patients given opioid treatment by emergency medical services with confirmed STEMI were included in this secondary, retrospective cohort analysis of the Air versus Oxygen in Myocardial Infarction (AVOID) study. Patients with cardiogenic shock were excluded. The primary endpoint was comparison of cardiac biomarkers as a measure of infarct size based on opioid dose (low ≤8.75 mg, intermediate 8.76-15 mg and high >15 mg of intravenous morphine equivalent dose). RESULTS: 422 patients were included in the analysis. There was a significantly higher proportion of patients with Thrombolysis in Myocardial Infarction (TIMI) 0 or 1 flow pre-percutaneous coronary intervention (PCI) (94% vs 81%, p=0.005) and greater use of thrombus aspiration catheters (59% vs 30%, p