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.

Magnesium Sulfate versus Placebo for Paroxysmal Atrial Fibrillation: A Randomized Clinical Trial

“…In a placebo-controlled RCT similar to ours, Walker et al 5 investigated the acute effects of magnesium in AF and flutter with a rapid ventricular rate. They gave MgSO 4 20 mmol IV over 30 minutes to 21 patients and placebo to another 20 patients.…”

“…Previous studies have reported a fall in heart rate in patients with AF from a mean (±SD) of 130-140 (±20-30) beats ⁄ min to about 100 beats ⁄ min after treatment with MgSO 4 and using a heart rate < 100 beats ⁄ min as an endpoint. [3][4][5][6][7][8] Based on these reports, we estimated that just over 20 patients were needed in each of the two treatment groups in our study to detect a differential fall in mean (±SD) ventricular rate from 125 to 100 (±25) beats ⁄ min at 2 hours after starting the trial drugs. Calculation was based on a comparison of two means posttreatment with power set at 90% and level of significance at 5%.…”

“…More commonly, previous investigators have compared magnesium in addition to standard therapy against standard therapy alone. Standard therapies have included a variety of antiarrhythmic agents including digoxin, [3][4][5]11 verapamil, 6,7 diltiazem, 8 and amiodarone. 12 These studies have all reported apparent benefits of magnesium in the treatment of supraventricular tachyarrhythmias, including AF.…”

“…Their meta-analysis pooled four trials (303 patients) and eight trials (476 patients), respectively, for acute rate control (<100 beats ⁄ min) and rhythm control and included the trials by Davey and Teubner 5 and Walker et al 11 The therapies against which magnesium was compared in these pooled trials were varied. Magnesium or placebo was given in addition to standard therapy.…”

Use of intravenous magnesium to treat acute onset atrial fibrillation: a meta-analysis

“…The 10 included trials involved data from six countries and all were published in English (table 1). Three trials involved patients in the emergency department,21 23 24 three trials involved patients in the intensive care unit,17 20 27 and three trials involved patients in the cardiology department or ward 22 25 26. One trial did not specify the hospital location of the patients in the trial 28.…”