[Magnesium therapy in acute myocardial infarction. New points of view].

In some smaller placebo-controlled, randomized studies, and in one larger such study (LIMIT-2, 2,136 patients), intravenous infusion of magnesium was shown to reduce early and late mortality of ischaemic heart disease in patients admitted with suspected acute myocardial infarction. In contrast, the ISIS-4 trial, which included 58,050 patients, did not show any benefit from magnesium. These discrepancies may be explained as follows; In LIMIT-2, magnesium was given early and before spontaneous or therapeutic thrombolysis (36% of the patients), in ISIS-4, however, the patients were likely to have undergone myocardial reperfusion in response to thrombolysis (70% of the patients) before receiving magnesium. Myocardial stunning may develop in association with reperfusion. Magnesium given before and during ischaemia attenuates postischaemic myocardial dysfunction. The absence of effect of magnesium in ISIS-4 is also thought to be related to the higher dose administered during the first 24 hours in this study. Early infusion of magnesium in acute myocardial infarction is a useful addition to standard therapy, and is simple, cheap and safe to administer.