Background & objectives: Cardiac arrhythmia after CABG surgery is a common complication which results in other side effects. Therapeutic effect of prophylactic magnesium administration is controversial and there are many different ideas in this case. The aim of this study was to evaluate the therapeutic effects of magnesium in reducing cardiac arrhythmia after CABG.

Methods: The clinical trial enrolled 140 patients undergoing CABG. Based on the initial blood levels of magnesium, patients were divided into two groups, one group with low serum magnesium and the other group with normal one. The low serum magnesium group treated with magnesium preoperatively and had normal serum magnesium level before operation. Postoperatively, both groups were randomly divided into two sub-groups, one receiving 2 gr. of magnesium sulfate and the other group received placebo. Both groups monitored for occurrence of arrhythmia in the ICU – OH for 3 days. Data were analyzed with statistical methods. P value of <0.05 was considered statistically significant.

Results: The results showed that the occurrence of arrhythmia in any of the sub-groups was not significantly different from each other (p> 0.05). There was no significant relationship between blood levels of magnesium and arrhythmia at different days (p> 0.05).

Conclusions: Blood level of magnesium and prophylactic magnesium administration have not effect on reducing arrhythmia after CABG surgery. The highest incidence of arrhythmias happened in the hypomagnesium group without prophylaxis on the third day after surgery, but this difference was not statistically significant.