This alternative treatment would avoid the use of morphine, whose potentially damaging consequences on myocardial function have been suggested by experimental studies and by an observational study. The physician of the mobile emergency team (SMUR) verifies the inclusion and non- inclusion criteria for the study. The patient must present STEMI defined in accordance with the recommendations and chest pain of intensity ≥ 4 on the NRS. The specific treatment for STEMI will be given before inclusion in the study, with the exception of analgesic treatment. In particular, inclusion in the study must not delay the initiation of strategies of recanalization and reperfusion.