Key result
Magnesium supplementation was associated with a 3% decreased relative risk and a 0.6% absolute risk reduction of experiencing an atrial fibrillation event in critical care patients.
Why the study?
Magnesium supplementation to prevent atrial fibrillation is common in critical care, but no randomised studies support this practice in non-cardiac surgery critical care populations, leaving its effectiveness unclear.
Does magnesium supplementation prevent the onset of atrial fibrillation in adult critical care patients?
Observational (n=1,914)
No
Does magnesium supplementation prevent the onset of atrial fibrillation in adult critical care patients?
Effect estimate: ARR 0.6% (95% CI -0.06 to -0.004)
Absolute Event Rate: 1.42% vs 2.03%
p-value: p=0.03
Routine magnesium supplementation in a general critical care population is associated with a small but significant reduction in the risk of developing atrial fibrillation.
May reduce AF risk in critical care; hypothesis-generating and should not change practice without RCTs.
Atrial fibrillation is a frequently encountered condition in critical illness and causes adverse effects including haemodynamic decompensation, stroke and prolonged hospital stay. It is a common practice in critical care to supplement serum magnesium for the purpose of preventing episodes of atrial fibrillation. However, no randomised studies support this practice in the non-cardiac surgery critical care population, and the effectiveness of magnesium supplementation is unclear. We sought to investigate the effectiveness of magnesium supplementation in preventing the onset of atrial fibrillation in a mixed critical care population. We conducted a single centre retrospective observational study of adult critical care patients. We utilised a natural experiment design, using the supplementation preference of the bedside critical care nurse as an instrumental variable. Using routinely collected electronic patient data, magnesium supplementation opportunities were defined and linked to the bedside nurse. Nurse preference for administering magnesium was obtained using multilevel modelling. The results were used to define "liberal" and "restrictive" supplementation groups, which were inputted into an instrumental variable regression to obtain an estimate of the effect of magnesium supplementation. 9114 magnesium supplementation opportunities were analysed, representing 2137 critical care admissions for 1914 patients. There was significant variation in magnesium supplementation practices attributable to the individual nurse, after accounting for covariates. The instrumental variable analysis showed magnesium supplementation was associated with a 3% decreased relative risk of experiencing an atrial fibrillation event (95% CI - 0.06 to - 0.004, p = 0.03). This study supports the strategy of routine supplementation, but further work is required to identify optimal serum magnesium targets for atrial fibrillation prophylaxis.
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Wilson et al. (2022) conducted an observational in Critical illness (atrial fibrillation prophylaxis) (n=1,914). Magnesium supplementation vs. Restrictive supplementation practice was evaluated on New onset atrial fibrillation (ARR 0.6%, 95% CI -0.06 to -0.004, p=0.03). Magnesium supplementation was associated with a 3% decreased relative risk and a 0.6% absolute risk reduction of experiencing an atrial fibrillation event in critical care patients.
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