Batchelor R, et al. - Researchers investigated if and how clinical results [in-hospital or 30-day myocardial infarction and in-hospital or 30-day mortality] in patients receiving primary percutaneous coronary intervention for ST-elevation myocardial infarction could be influenced by periprocedural intravenous morphine administration. They searched electronic databases of MEDLINE, EMBASE, Cochrane Central Register of Controlled Trials, Scopus, Web of Science and ClinicalTrials.gov to identify the relevant studies. A systematic review was performed including 11 studies (1 randomized controlled trial, 10 observational studies). A meta-analysis was also conducted including five studies with 3,748 patients. Findings revealed no link between periprocedural intravenous morphine administration and adverse short-term clinical results in this patient population.