The value of intravenous magnesium treatment in patients with acute myocardial infarction is controversial. Magnesium therapy reduced the mortality in animal studies and in ten smaller clinical trials. The beneficial effect was due to the reduced infarct size and the limitation of reperfusion injuries. Magnesium may protect myocytes via several mechanisms: (1) reduced vulnerability to oxygen-derived free radicals, (2) decreased cytosolic calcium levels by inhibition of inward flux of calcium ions, (3) reduced myocardial oxygen demand via sinus slowing and lowering of blood pressure, (4) coronary vasodilatation and enhancement of collateral development, and (5) inhibition of platelet aggregation. Magnesium decreased the myocardial necrosis and reduced the mortality only in those studies when it was administered in the early phase of the acute myocardial infarction, before or within a very short interval after reperfusion achieved either spontaneous or via thrombolysis. Mortality reduction with magnesium was the greatest in patients with the highest baseline risk. There was a considerable benefit of magnesium treatment in the elderly and in patients who were not candidates for thrombolytic therapy. In contrast to several smaller studies, however the magnesium sulphate did not decrease the mortality of patients with acute myocardial infarction in a large, international randomized trial of 58 050 patients (ISIS-4). The inefficiency of magnesium treatment in ISIS- 4 may have been due to the late administration of magnesium to inherently lowrisk patients. In patients receiving thrombolytic therapy magnesium infusions were delayed 1 to 2 hours after the fibrinolytic treatment in ISIS- 4. The time of magnesium administration is probably critical in order to achieve the benefit of this treatment. Magnesium may decrease myocardial damage and reduces mortality if it is administered before reperfusion occurs.
|Translated title of the contribution||Magnesium therapy in acute myocardial infarction|
|Number of pages||6|
|Journal||Lege Artis Medicinae|
|Publication status||Published - Dec 1 1996|
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