Objective: To evaluate the effect of intravenous magnesium, on prevention of postoperative cardiac arrhythmias after open cardiac surgery.

Methodology: Prospective interventional study was conducted at Department Of Cardiac Surgery Punjab Institute Of Cardiology, Lahore from 1st August 2011 to 31st March 2012. Study groups included 260 consecutive patients undergoing CABG having normal sinus rhythm. They were classified as group I receiving magnesium supplementation perioperatively & group II not receiving magnesium supplementation. Intravenous Magnesium was administered before weaning from CPB and on 1st postoperative day. Twelve-lead electrocardiograms were obtained immediately after operation and daily until detection of new onset arrhythmias. The distribution of both groups in CABG patients was compared for rhythm disorders.

Results: The mean age of patients was 51.73±10.16 years. A total of 41 patients developed arrhythmias postoperatively. There was no mortality during the study in that specific group. Other analysis indicates there is an effect of intravenous Mg on the prevention of post cardiac arrhythmia after open heart surgery.

Conclusion: Prophylactic administration of intravenous magnesium is associated with low incidence of postoperative cardiac arrhythmias.