MAGNEsium With meToprolol for Rate Control In Atrial Fibrillation

Intravenous magnesium has become a commonly utilized agent in the treatment of cardiac arrhythmias as an adjunct therapy to rate and rhythm control medications, such as its use in atrial fibrillation or atrial flutter with rapid ventricular response (AFF RVR). Though its benefit in the treatment of AFF RVR has been well documented, a consensus on the optimal dosing of magnesium has yet to be achieved. Only one randomized, controlled, double-blinded study has investigated the optimal dosing of magnesium. The purpose of this prospective, randomized, double-blinded study is to further evaluate the safety and efficacy of varying doses of intravenous magnesium in the treatment of atrial fibrillation or atrial flutter with rapid ventricular response. This study will use flat-dose intravenous metoprolol for rate control to minimize confounders. Additionally, this study will not require a resulted magnesium level prior to treatment in order to avoid delays in patient care.

Inclusion criteria

• Age > 18 years or older
• Able to provide informed consent
• Primary diagnosis atrial fibrillation or atrial flutter with rapid ventricular response (AFF RVR) greater than or equal to 120 beats per minute
• Metoprolol as rate control agent
• English speaking

Exclusion criteria

• Hemodynamically unstable patients (SBP <90, MAP <65)
• Impaired consciousness
• Acute heart failure exacerbation based on clinical diagnosis, physician exam, bedside echo, and/or additional imaging
• Patient in AFF RVR that is highly suspected to be a compensatory mechanism for an alternative clinical diagnosis
• Rhythms other than atrial fibrillation, such as sick sinus syndrome or wide-complex ventricular response
• Acute myocardial infarction
• Contraindications to magnesium sulfate (including myasthenia gravis)
• Allergy or sensitivity to any study drugs
• Previously enrolled in this trial during a different patient encounter
• Withdrew from study