Acute myocardial infarction (AMI) is usually due to thrombotic occlusion of coronary arteries.Interacellular magnesium decreases after AMI. One of the drugs in treatment of AMI is parenteral magnesium sulphate that its efficacy is still ambiguous in decreasing ventricular arrhythmia and in-hospital mortality rate.We decided to investigate magnesium efficacy in in-hospital prognosis of AMI.

This study was a double blind randomized clinical trial.Sixty patients with AMI were randomized equally in two groups(one magnesium sulphate and other DW 5% as placebo).Magnesium sulphate infused at arrival to the patients(8 mmol in the first 5 minutes and 65 mmol in next 24 hours) and the patients in two groups were compared with respect to frequency of in-
   hospital mortality rate,ventricular arrhythmia and ejection fraction.

Age, sex and AMI-type distribution in two groups were not significantly different. The frequency of ventricular arrhythmia in treatment and placebo group was 7(23.3%) and 19(63.3%) respectively, which was statistically different (P=0.002). In-hospital mortality rate after AMI was one(3.3%) in treatment group and 4(13.3%) in placebo group that was not significantly different (P=0.177). Also mean of EF in treatment and placebo group was
   54.3% and 46.5% respectively (P=0.003).

         Results showed that parenteral magnesium sulphate was efficient in decreasing ventricular arrhythmia after AMI.Ejection fraction was also increased significantly after magnesium sulphate therapy. In spite of decrease in mortality rate, the difference was not statistically significant.