The acute effects of magnesium in atrial fibrillation and flutter with a rapid ventricular rate

Abstract A prospective, randomised, placebo controlled, double blinded trial to assess the efficacy of intravenous magnesium sulphate (20mmol over 30 minutes) versus placebo in patients presenting to the emergency department with rapid atrial fibrillation and flutter. The end points were slowing of the ventricular rate and reversion to sinus rhythm. A total of 41 patients were enrolled. The mean decrease in heart rate 30 minutes after commencing the infusion was 24.1/min for the magnesium group compared to 11.0/min for the placebo group (different at the 95% level of significance). The mean decrease in heart rate and the reversion rate four hours after commencing the infusion were the same at the 95% level of significance for the two groups. We conclude that magnesium has a significant effect in the acute slowing of ventricular rate but no effect in achieving reversion to sinus rhythm.