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Magnesium, a safe and inexpensive treatment for atrial fibrillation

Magnesium, a safe and inexpensive treatment for atrial fibrillation

Intravenous magnesium sulfate (MgS), when combined with other atrioventricular (AV) nodal blockers, appears to have a synergistic effect in improving rate control of rapid atrial fibrillation (AF) in the emergency department (ED). 4.5 and 9g of MgS had similar efficacy, however, a dose of 9g was associated with more side effects.

These are the findings of a new study published in the journal Academic Emergency Medicine.

Semir Nouira, Emergency Department, Fattouma Bourguiba University Hospital, Monastir, Tunisia, and colleagues conducted the study to determine the benefit of two different doses MgS compared to placebo in rate control of rapid AF managed in the ED.
This study hold importance as magnesium is a safe and inexpensive way of prolonging the AV node refractory period. The recent meta-analysis has suggested benefit for AF treatment, but studies have some important limitations.
The authors undertook a randomized, controlled, double‐blind clinical trial in 3 university hospital EDs between August 2009 and December 2014. The patients >18years having apid AF (>120 bpm) were enrolled and randomized to 9g intravenous MgS (High dose group, n=153), 4.5 g intravenous MgS (Low dose group, n=148), or serum saline infusion (placebo group, n=149), given in addition to atrioventricular (AV) nodal blocking agents.
The primary outcome was a reduction of baseline ventricular rate (VR) to 90 beats/min or less, or a reduction of VR by 20% or greater from baseline (therapeutic response). Secondary outcome included sinus rhythm conversion rate, resolution time [defined as the elapsed time from start of treatment to therapeutic response] and adverse events within the first 24 hours.
Key Findings:
  • At 4 hours, the therapeutic response rate was higher in low and high MgS groups compared to placebo group, the absolute difference was respectively 20.5% (risk ratio [RR] 2.31; 95% CI 1.45‐3.69) and +15.8% (RR 1.89; 95% CI 1.20‐2.99).
  • At 24 hours, compared to placebo group, therapeutic response difference was +14.1% (RR 9.74; 95% CI 2.87‐17.05) with low dose MgS and +10.3% (RR 3.22; 95% CI 1.45‐7.17) with high dose MgS.
  • The lowest resolution time was observed in low dose MgS group (5.2±2 hours) compared to 6.1±1.9 hours in High dose MgS group and 8.4±2.5 hours in the placebo group. Rhythm control rate at 24 hours was significantly higher in low dose MgS group (22.9%) compared to High dose MgS group (13.0%, p=0.03) and placebo group (10.7%).
  • Adverse effects were minor and significantly more frequent with a high dose of MgS.

“Our findings demonstrate that intravenous MgS appears to have a synergistic effect when combined with other AV nodal blockers resulting in improved rate control of atrial fibrillation. Similar efficacy was observed with a low dose (4.5 and 9g) of MgS but a high dose of 9g was associated with more side effects,” concluded the authors.

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Source: With inputs from Academic Emergency Medicine

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