Original Article
Continuous Magnesium Infusion to Prevent Atrial Fibrillation After Cardiac Surgery: A Sequential Matched Case-Controlled Pilot Study

https://doi.org/10.1053/j.jvca.2020.04.006Get rights and content

Objective

The authors aimed to test whether a bolus of magnesium followed by continuous intravenous infusion might prevent the development of atrial fibrillation (AF) after cardiac surgery.

Design

Sequential, matched, case-controlled pilot study.

Setting

Tertiary university hospital.

Participants

Matched cohort of 99 patients before and intervention cohort of 99 consecutive patients after the introduction of a continuous magnesium infusion protocol.

Interventions

The magnesium infusion protocol consisted of a 10 mmol loading dose of magnesium sulphate followed by a continuous infusion of 3 mmol/h over a maximum duration of 96 hours or until intensive care unit discharge.

Measurements and Main Results

The study groups were balanced except for a lower cardiac index in the intervention cohort. The mean duration of magnesium infusion was 27.93 hours (95% confidence interval [CI]: 24.10-31.76 hours). The intervention group had greater serum peak magnesium levels: 1.72 mmol/L ± 0.34 on day 1, 1.32 ± 0.36 on day 2 versus 1.01 ± 1.14 and 0.97 ± 0.13, respectively, in the control group (p < 0.01). Atrial fibrillation occurred in 25 patients (25.3%) in the intervention group and 40 patients (40.4%) in the control group (odds ratio 0.49, 95% CI, 0.27-0.92; p = 0.023). On a multivariate Cox proportional hazards model, the hazard ratio for the development of AF was significantly less in the intervention group (hazard ratio 0.45, 95% CI, 0.26-0.77; p = 0.004).

Conclusion

The magnesium delivery strategy was associated with a decreased incidence of postoperative AF in cardiac surgery patients. These findings provide a rationale and preliminary data for the design of future randomized controlled trials.

Section snippets

Study Design

The authors performed an investigator-initiated, sequential matched case-controlled pilot study in the multidisciplinary ICU of Austin Hospital, a tertiary care hospital in Melbourne, Australia. The intervention phase of the study was conducted from September 25, 2017 to June 22, 2018. The study was approved by the Human Research Ethics Committee of Austin Health (HREC reference number LNR/17/Austin/416) as a unit practice change protocol with a waiver for informed consent. The study was

Patient Characteristics

The authors enrolled 99 patients in the intervention group and matched them with 99 patients in the historical control group. The flowchart of the study enrollment of the intervention group patients and the selection process of the historical control group are demonstrated in Figure 2. The patient groups had similar baseline characteristics, except for a lower cardiac index at admission to the ICU in the intervention group (Table 1).

Magnesium Delivery in the Intervention Group

In the intervention group, 71 patients (71.7%) received a

Key Findings

In this single-center matched case-control sequential pilot study, the authors observed a reduced occurrence of newly diagnosed postoperative AF after cardiac surgery in patients who received a postoperative strategy of bolus loading and continuous intravenous magnesium delivery to target a magnesium level between 1.5 and 2 mmol/L compared with a matched pre-intervention control group. Moreover, although the study intervention resulted in a significant increase in serum magnesium levels as

Conclusion

The authors conducted a sequential matched case-controlled pilot study to assess the impact of a continuous magnesium delivery strategy targeting a magnesium level between 1.5 and 2.0 mmol/L. The authors found that such a strategy was associated with a significant decrease in the incidence of AF after cardiac surgery and was free of major complications. These observations provide the rationale for testing the efficacy of this magnesium delivery protocol in future randomized controlled studies.

Conflict of Interest

Declarations of interest: none.

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  • Financial support for this study was received from the Anesthesia and Intensive Care Trust Fund, Austin Hospital. The funding source had no involvement in study design; in the collection, analysis, and interpretation of data; in the writing of the manuscript; and in the decision to submit the article for publication.

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