Magnesium in Atrial Fibrillation: Does it Cardiovert?

A 63 yo patient presents to the emergency department at 11pm at night in new atrial fibrillation with a ventricular rate of 167 bpm. There is no past medical history apart from migraine for which the patient is already on metoprolol. Bloods come back essentially normal. A decision is made to see if the patient will self-revert…… all very reasonable.

The next thing that seems to go up always is IV Magnesium and sometimes Potassium. Does magnesium work? Does it add anything? Do you use it? In deciding who to use magnesium on, we need to think about a few things, including patient selection and safety of the drug.

Let’s have a look at the evidence. Let’s look at the controversy. Spoiler alert; It’s a safe drug, causing very few side effects. It may reduce the ventricular rate when given with another rate control agent, but probably doesn’t cardiovert.