Original article
Cardiovascular
Three-Day Magnesium Administration Prevents Atrial Fibrillation After Coronary Artery Bypass Grafting

https://doi.org/10.1016/j.athoracsur.2004.06.062Get rights and content

Background

The efficacy of magnesium administration in preventing the occurrence of atrial fibrillation after coronary artery bypass grafting surgery remains controversial. Optimal dose and timing of the administration also await clarification. The purpose of this study was to assess the effect of 3-day postoperative infusion of magnesium on postoperative atrial fibrillation and to find factors that can influence the efficacy of this treatment.

Methods

After institutional review board approval, a retrospective study was conducted reviewing 200 consecutive patients who underwent isolated, initial coronary artery bypass grafting operation. The first 100 patients did not receive the prophylactic treatment, whereas the next 100 patients were treated with magnesium postoperatively. Patients in the magnesium-treated group received 10 mmol (2.47 g) of magnesium sulfate (MgSO4 · 7H2O) infused daily for 3 days after surgery.

Results

The incidence of postoperative atrial fibrillation was 35% in the untreated group compared with 16% in the magnesium-treated group (p = 0.002). Multivariate logistic regression analysis revealed that advanced age, decreased left ventricular ejection fraction, and absence of magnesium therapy were independent predictors of postoperative atrial fibrillation. For patients receiving the magnesium therapy, advanced age and decreased ejection fraction were the independent factors that predicted the arrhythmia.

Conclusions

Postoperative 3-day magnesium infusion is effective in reducing the incidence of atrial fibrillation occurring after coronary artery bypass grafting surgery. However, in older patients or in patients with reduced left ventricular function, magnesium treatment alone is insufficient for prophylaxis of postoperative atrial fibrillation.

Section snippets

Study Population

A retrospective study was conducted reviewing all patients who had undergone isolated, initial CABG at Sakakibara Heart Institute, Tokyo, Japan, before and after the time point when the magnesium supplementation protocol was initiated (April 1, 2002). Exclusion criteria included history of AF or other supraventricular arrhythmias (including paroxysmal supraventricular arrhythmias), implanted permanent pacemaker, postoperative myocardial infarction, and severe hemodynamic disorder requiring

Results

The incidence of postoperative AF was 16% (16 patients) in the magnesium-treated group and 35% (35 patients) in the untreated group (p = 0.002). Regarding time of AF onset and duration of postoperative hospital stay, no statistically significant difference was found between the two groups (Table 2).

Mean serum magnesium concentration decreased to subnormal value (reference range, 1.8 to 2.6 mg/dL) immediately after surgery in both magnesium-treated and untreated groups (Fig 1). The two groups

Comment

The reported incidences of AF after CABG range from 10% to 50% 1, 5, 6. Despite recent improvements in perioperative management, its occurrence has not decreased during the years and is associated with significant morbidity. Given this consequence, a wide variety of prophylactic strategies have been evaluated, including perioperative magnesium administration; at present, the efficacy of this treatment is still controversial. In the 100 consecutive patients we reviewed who did not receive the

Acknowledgement

This study could not have been performed without the support and cooperation of the medical and nursing staff of the intensive care and cardiovascular surgical units of Sakakibara Heart Institute. Deep appreciation is extended to Ryo Hoshino, MD, Ikuko Shibazaki, MD, Keima Nagamachi, MD, Hiroki Hayashi, MD, Naoki Wada, MD, Tomoki Shimokawa, MD, and Takao Ida, MD, for their contributions and technical assistance in the preparation of the study. We also thank the cardiovascular staff of Chiba

References (29)

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