Low Versus High Dose Magnesium Sulfate in the Early Management of Rapid Atrial Fibrillation

Introduction:

Atrial fibrillation (AF) is a potentially life-threatening cardiac arrhythmia and a frequent chief complaint in emergency departments (ED). It is an important concern for a substantial proportion of people worldwide. According to the Rotterdam study, the prevalence of AF among individuals aged between 55 to 59 years is estimated at 1.1 for 1000 persons/year and 20.7 for individuals between 80 and 84 years. Given current adult advanced cardiac life support (ACLS), the immediate clinical objective in rapid AF is to achieve ventricular rate control. Digoxin, beta blockers and calcium channel antagonists are the most widely used agents for the emergent treatment of rapid AF. However, their effect is limited because only half of the patients will acutely respond to the first intention treatment. Several studies showed that the magnesium sulfate (MgS) is beneficial in the control of the rate and the rhythm of AF. In addition, hypomagnesemia is present among patients having AF in 20 to 53% of the cases . The association of hypomagnesemia and AF is common after a cardiac surgery and the prophylactic administration of MgS could be useful in post-operative AF .

The last meta analysis published in 2007 showed that the MgS is as well efficient in rate control (OR = 1.96) as in rhythm control (OR = 1.60) of AF. However most studies included in this meta analysis were conducted on limited number of patients (303 patients included for rate control outcome analysis and 376 for rhythm control). Consequently we need further randomized controlled studies to establish definitively the efficacy and the safety of MgS in the early management of rapid AF.

Objective:

To assess the efficacy and the safety of high (9g) and low dose (4.5g) of MgS in the immediate treatment of rapid AF.

Inclusion criteria

• All patients presenting to ED with rapid AF (Heart rate >120 bpm).

Exclusion criteria

• Unstable hemodynamic state.
• Renal insufficiency (creatinemia> 180 µmol/l).
• Allergy to MgS.