A Randomized Controlled Trial of Magnesium Sulfate, in Addition to Usual Care, for Rate Control in Atrial Fibrillation
Received 22 April 2004; received in revised form 9 September 2004; accepted 15 September 2004. published online 07 February 2005.
Study objectives
We examine the safety and efficacy of magnesium sulfate infusion, in addition to usual care, for acute rate reduction in patients with atrial fibrillation and a rapid ventricular response rate.
Methods
This was a prospective, randomized, double-blind, placebo-controlled trial of intravenous magnesium sulfate in adult emergency department patients with rapid atrial fibrillation. Study solutions were given in addition to any therapy the treating physician would normally consider appropriate, including the use of standard rate-reduction agents. Patients received either 20 mEq (2.5 g, 10 mmol) magnesium sulfate over a 20-minute period, followed by 20 mEq (2.5 g, 10 mmol) over a 2-hour period intravenously, or placebo.
Results
One hundred ninety-nine patients were randomized, 102 to receive magnesium sulfate and 97 to receive placebo. The antiarrhythmic drug most commonly used by treating physicians was digoxin. Magnesium sulfate was more likely than placebo to achieve a pulse rate of less than 100 beats/min (63 [65%] of 97 versus 32 [34%] of 93, relative risk [RR] 1.89; 95% confidence interval [CI] 1.38 to 2.59; P<.0001) and more likely to convert to sinus rhythm (25 [27%] of 94 patients versus 11 [12%] of 91 patients; RR 2.20; 95% CI 1.15 to 4.21; P=.01). Comparative mean pulse rate reductions in the magnesium sulfate group did not reach predetermined clinical significance levels (≥15 beats/min reduction) at any of the measured time points. Magnesium sulfate was more likely to be associated with an adverse event (14 [15%] of 95 patients versus 5 [5%] of 92 patients; RR 2.71; 95% CI 1.02 to 7.23; P=.04).
Conclusion
Magnesium sulfate, when used to supplement other standard rate-reduction therapies, enhances rate reduction and conversion to sinus rhythm in patients with rapid atrial fibrillation.
From the Department of Emergency Medicine, Royal Adelaide Hospital, North Terrace, Adelaide, South Australia, Australia (Davey); the Department of Medicine, Adelaide University, Adelaide, South Australia, Australia (Davey); and the Department of Emergency Medicine, Flinders Medical Centre, Bedford Park, South Australia, Australia (Teubner)
Address for correspondence: Michael John Davey, MBBS, FACEM, Emergency Department, Royal Adelaide Hospital, North Terrace, Adelaide, South Australia, Australia 5000; 61-08-8222-5063, fax 61-08-8222-4970
Author contributions: MJD conceived and designed the study. MJD and DT collected and analyzed the data and wrote the manuscript. MJD takes responsibility for the paper as a whole.
Funding and support: The authors report this study did not receive any outside funding or support.
ABSTRACT