Acute myocardial infarction is a major cause of mortality and morbidity. Primary percutaneous
coronary intervention (pPCI) is currently the most effective treatment strategy in acute
myocardial infarction. However, a sizable number of patients fail to restore optimal
myocardial reperfusion, mostly because of the 'no-reflow' phenomenon. Melatonin is the chief
indoleamine produced by the pineal gland, and a well-known antioxidant and free radical
scavenger. Several studies have shown that melatonin protects against ischemia/reperfusion
injury (IRI). In our previous study, melatonin markedly reduced infarcted area, improved
cardiac function and reduced lactate dehydrogenase release in rats. The investigators planned
to research the cardioprotective effects of intravenous melatonin administered prior to
reperfusion and continued after restoration of coronary blood flow in patients with ST
segment elevation myocardial infarction undergoing pPCI.