A randomized controlled trial of magnesium sulfate, in addition to usual care, for rate control in atrial fibrillation.
OBJECTIVE
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 (> or =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).


CONCLUSIONS
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.
Davey
Michael John
MJ
Department of Emergency Medicine, Royal Adelaide Hospital, North Terrace, Adelaide, South Australia, Australia. mdavey@mail.rah.sa.gov.au
Teubner
David
D
D000368:Aged; D000369:Aged, 80 and over; D000889:Anti-Arrhythmia Agents / Q000009:adverse effects / Q000627:therapeutic use*; D001281:Atrial Fibrillation / Q000188:drug therapy* / Q000503:physiopathology; D001283:Atrioventricular Node / Q000187:drug effects; D004311:Double-Blind Method; D004359:Drug Therapy, Combination; D004636:Emergency Service, Hospital; D005260:Female; D006339:Heart Rate / Q000187:drug effects; D006352:Heart Ventricles / Q000503:physiopathology; D006801:Humans; D008278:Magnesium Sulfate / Q000009:adverse effects / Q000627:therapeutic use*; D008297:Male; D008875:Middle Aged
D000889:Anti-Arrhythmia Agents; D008278:Magnesium Sulfate