[Magnesium treatment of patients with acute myocardial infarction. A meta-analysis]

The object of the study was to investigate the effect of intravenous magnesium in acute myocardial infarction. It was carried out as an overview of available randomized trials in which patients were allocated to receive either magnesium or placebo, the trials having taken place in the coronary care units of several hospitals. The subjects were 2438 patients with acute myocardial infarction in nine blind randomized trials combined in a meta-analysis and 54,822 patients in one unblinded randomized multi-centre trial. The main outcome measure was the relative chance of survival and relative chance of avoiding ventricular tachyarrhythmia. In the meta-analysis, the relative chance of survival was significantly increased in the magnesium group (RR = 1.049, 95% CI = 1.020-1.078, p < 0.0007). Hypothetically 25 papers with a mean of 271 patients and an RR of 1.0 should be included to make the result insignificant. The relative chance of avoiding ventricular tachyarrhythmia was not significantly increased in the magnesium group (RR = 1.041, 95% CI = 0.996-1.089, p = 0.07). The risk of accepting the null hypothesis (RR = 1.0) if the alternative hypothesis (RR = 1.041) is correct is 0,58 (the type 2 error). There was no effect on survival in the multi-centre study (RR = 0.996). It is concluded that intravenous treatment with magnesium increases survival in patients with acute myocardial infarction by 4.9% in nine blind trials, but has no effect in a large open multi-centre study.