Efficacy of Intravenous Magnesium in Facilitating Cardioversion of Atrial Fibrillation

Clinician preference instrumental variable analysis of the effectiveness of magnesium supplementation for atrial fibrillation prophylaxis in critical care

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.

The Role of Hypomagnesemia in Cardiac Arrhythmias: A Clinical Perspective

The importance of magnesium (Mg²⁺), a micronutrient implicated in maintaining and establishing a normal heart rhythm, is still controversial. It is known that magnesium is the cofactor of 600 and the activator of another 200 enzymatic reactions in the human organism. Hypomagnesemia can be linked to many factors, causing disturbances in energy metabolism, ion channel exchanges, action potential alteration and myocardial cell instability, all mostly leading to ventricular arrhythmia. This review article focuses on identifying evidence-based implications of Mg²⁺ in cardiac arrhythmias. The main identified benefits of magnesemia correction are linked to controlling ventricular response in atrial fibrillation, decreasing the recurrence of ventricular ectopies and stopping episodes of the particular form of ventricular arrhythmia called torsade de pointes. Magnesium has also been described to have beneficial effects on the incidence of polymorphic ventricular tachycardia and supraventricular tachycardia. The implication of hypomagnesemia in the genesis of atrial fibrillation is well established; however, even if magnesium supplementation for rhythm control, cardioversion facility or cardioversion success/recurrence of AF after cardiac surgery and rate control during AF showed some benefit, it remains controversial. Although small randomised clinical trials showed a reduction in mortality when magnesium was administered to patients with acute myocardial infarction, the large randomised clinical trials failed to show any benefit of the administration of intravenous magnesium over placebo.

Intravenous Magnesium Sulfate Reduces the Need for Antiarrhythmics during Acute-Onset Atrial Fibrillation in Emergency and Critical Care

Several studies have suggested the potential role of Magnesium Sulfate (MgSO4) for the treatment of Atrial Fibrillation (AF) but, in clinical practice, the use of magnesium is not standardized although it is largely used for the treatment of supraventricular arrhythmias. Objectives. We evaluated the role of MgSO4 infusion in association with flecainide in cardioversion of patients presenting in ED with symptomatic AF started less than 48 h before. We retrospectively searched for all patients presented in ED from 1 January 2019 to 31 December 2019 requiring pharmacological cardioversion with flecainide 2 mg/kg. Ninety-seven patients met these criteria, 46 received the administration of intravenous MgSO4 2 gr (Group A), and 51 did not (Group B). Among the 97 patients, the overall cardioversion rate was 85.6%, 91.3% in Group A and 80.4% in Group B. In 27 patients out of 97, the Flecainide was not administered because of spontaneous restoration of sinus rhythm of 9 pts (Group B) and 18 pts (Group A). We also found a statistical significance in the HR at the time of cardioversion between Group A (77.8 ± 19.1 bpm) and Group B (87 ± 21.7 bpm). No complications emerged. The association between MgSO4 and Flecainide has not yielded statistically significant results. However, in consideration of its high safety profile, MgSO4 administration may play a role in ED cardioversion of acute onset AF, reducing the need for antiarrhythmic medications and electrical cardioversion procedures, relieving symptoms reducing heart rate, and reducing the length of stay in the ED.

Development of a Care Pathway for Atrial Fibrillation Patients in the Emergency Department

Atrial fibrillation (AF) is the most common cardiac arrhythmia and its prevalence is continuously increasing in the United States, leading to a progressive rise in the number of disease-related emergency department (ED) visits and hospitalizations. Although optimal long-term outpatient management for AF is well defined, the guidelines for optimal ED management of acute AF episodes is less clear. Studies have demonstrated that discharging patients with AF from the ED after acute stabilization is both safe and cost effective; however, the majority of these patients in the United States and in our institution are admitted to the hospital. To improve care of these patients, we established a multidisciplinary collaboration to develop an evidence-based systematic approach for the treatment and management of AF in the ED, that led to the creation of the University of California-Cardioversion, Anticoagulation, Rate Control, Expedited Follow-up/Education Atrial Fibrillation Pathway. Our pathway focuses on the acute stabilization of AF, adherence to best practices for anticoagulation, and reduction in unnecessary admissions through discharge from the ED with expedited outpatient follow-up whenever safe. A novel aspect of our pathway is that it is primarily driven by the ED physicians, while other published protocols primarily involve consulting cardiologists to guide management in the ED. Our protocol is very pertinent considering the current trend toward increased AF prevalence in the United States, coupled with a need for widespread implementation of strategies aimed at improving management of these patients while safely reducing hospital admissions and the economic burden of AF.

A randomized controlled trial of intravenous magnesium sulphate as an adjunct to standard therapy in atrial fibrillation

Background

Magnesium sulphate (MgSO4) has been proven as an analgesic, neuromuscular blocker agent, and treatment of acute asthma.

Objective

The study aimed to assess the safety and efficacy of magnesium sulphate infusion for the treatment of patients with atrial fibrillation.

Methods

A prospective, randomized, double-blind, placebo-controlled study was conducted on 55 atrial fibrillation patients at the Emergency Department. The treatment group consisting of 41 patients received 20 mEq (2.5 g, 10 mmol) magnesium sulphate over a 20-minute period, followed by 20 mEq (2.5 g, 10 mmol) over a 2-hour period intravenously in addition to the standard treatment, and the control group consisting of 14 patients received placebo with a standard treatment. ECG was repeated and monitored upto 24 hours after the infusion.

Results

41 patients received magnesium sulphate and 14 patients received a placebo. The heart rate was 127 bpm – 210 bpm at the presentation to the emergency department and it was reached <100bpm in 70%(n=31) patients after 150 minutes of MgSO4 infusion. Two patients attained a heart rate of <100bpm in Placebo infusion. In the treatment group, 65% of subjects attained normal sinus rhythm at the end of 24 hours of infusion. Magnesium sulphate was more likely than placebo to achieve a heart rate of <100bpm and more likely to convert to sinus rhythm. ECG report reverted to normal in 74.5% in the treatment group and 25.5 % in the Placebo group within 24 hours. The patients in the treatment group stay a mean of 2.25 days in ICU, while the patients in the Placebo group stayed 4.25 days in ICU. Seven patients in the treatment group had minor side effects like flushing, headache, and nausea, which came to normal after 48hrs.

Conclusions

Magnesium sulphate has been shown a better efficacy to control the heart rate and conversion to sinus rhythm when used along with the standard management of Atrial fibrillation.

A High-Value Care Initiative to Reduce the Use of Intravenous Magnesium Sulfate Through an Electronic Indication-Based Order Set

BACKGROUND

Intravenous (IV) magnesium sulfate (MgSO₄) supplementation is common despite limited indications. Oral magnesium oxide (MgO) is an effective, lower-cost alternative. This project aimed to reduce IV MgSO₄ use by 20% among the Internal Medicine (IM) service.

METHODS

Electronic health record (EHR) orders for MgSO₄ and MgO within the IM service were replaced with an indication-based EHR order panel. The project team educated clinicians regarding indications for IV MgSO₄ and relative costs. The mean of daily 2 g MgSO₄ administrations per week and the mean of weekly proportion of 2 g MgSO₄ administrations nine months before and after intervention were compared between IM and Emergency Medicine (EM) (control group). Statistical process control analysis was used to assess for special cause variation in daily MgSO₄ per week and weekly proportion of MgSO₄ administrations.

RESULTS

The mean of daily 2 g IV MgSO₄ administrations per week decreased among IM (19.3 vs. 12.1, p < 0.0001) but not EM (3.1 vs. 4.8, p < 0.0001). The mean of weekly proportions of IV MgSO₄ administrations decreased among both IM (83.6% vs. 60.7%, p < 0.0001) and EM (97.0% vs. 93.1%, p = 0.0004). For IM, the change in daily MgSO₄ per week and weekly proportion of MgSO₄ occurred as a discrete initial decline consistent with special cause variation; for EM, changes in both measures were not consistent with special cause variation.

CONCLUSION

Replacing stand-alone IV MgSO₄ orders with an indication-based order panel along with clinician education reduced IV MgSO₄ administrations and may offer a significant opportunity to reduce low-value care.

Utility of calcium, magnesium and phosphate testing in the emergency department

OBJECTIVE

To determine how frequently calcium (Ca), magnesium (Mg) and phosphate (PO₄ ) tests change ED patient management.

METHODS

We undertook a retrospective observational study in an Australian tertiary referral ED. We enrolled adult patients (aged ≥18 years) who presented between 1 January and 30 June 2017 and who had a serum Ca, Mg or PO₄ test ordered and completed during their ED stay. Patient symptoms, medical history, electrolyte levels and ED management changes were extracted from the electronic medical record.

RESULTS

Of the 33 120 adults presented during the study period, 1716 (5.2%, 95% confidence interval [CI] 5.0-5.4) had at least one Ca, Mg or PO₄ test completed in the ED. This included 4776 individual electrolyte tests, of which 776 (16.2%, 95% CI 15.2-17.3) were abnormal. Fifty-six (7.2% [95% CI 5.5-9.3] of patients with abnormal tests, 1.2% [95% CI 0.9-1.5] of all tests) tests were associated with a change in ED management. Twenty-six out of 1683 (1.5%) Ca levels were low with six (23.1%) management changes; 203 (12.1%) were high with 10 (4.9%) management changes. One hundred and twenty-eight out of 1579 (8.1%) Mg levels were low with 33 (25.8%) management changes; 30 (1.9%) were high with no management changes. Two hundred and twenty-five out of 1514 (14.9%) PO₄ levels were low with six (2.7%) management changes; 164 (10.8%) were high with one (0.6%) management change. Fifty (2.9%) patients had management changes despite normal electrolyte levels.

CONCLUSION

Ca, Mg and PO₄ testing is common. However, the yield of clinically significant abnormal levels is low and patient management is rarely changed. Testing of these electrolytes needs to be rationalised.

Effect of Dietary Factors on Cardiac Rhythm

The interaction between arrhythmias and certain lifestyle factors such as obesity and alcohol consumption is well-established. There is significant public and professional interest in the role of various diets, vitamins, and minerals in cardiovascular health. However, many widely held beliefs are not supported by the literature. There is limited evidence for routine magnesium and omega-3 poly-unsaturated fatty acids supplementation, while coffee, tea, nuts, antioxidant vitamins, and even chocolate may have some antiarrhythmic properties. Saturated fat, added salt, and excessive energy drink consumption appear to be harmful for patients with rhythm disorders. However most recommendations are based on observation studies, and this remains a fertile area for further research.

Magnesium and Cardiovascular Disease

Magnesium is the most abundant intracellular divalent cation and essential for maintaining normal cellular physiology and metabolism, acting as a cofactor of numerous enzymes, regulating ion channels and energy generation. In the heart, magnesium plays a key role in modulating neuronal excitation, intracardiac conduction, and myocardial contraction by regulating a number of ion transporters, including potassium and calcium channels. Magnesium also has a role in regulating vascular tone, atherogenesis and thrombosis, vascular calcification, and proliferation and migration of endothelial and vascular smooth muscle cells. As such, magnesium potentially has a major influence on the pathogenesis of cardiovascular disease. As the kidney is a major regulator of magnesium homeostasis, kidney disorders can potentially lead to both magnesium depletion and overload, and as such increase the risk of cardiovascular disease. Observational data have shown an association between low serum magnesium concentrations or magnesium intake and increased atherosclerosis, coronary artery disease, arrhythmias, and heart failure. However, major trials of supplementation with magnesium have reported inconsistent benefits and also raised potential adverse effects of magnesium overload. As such, there is currently no firm recommendation for routine magnesium supplementation except when hypomagnesemia has been proven or suspected as a cause for cardiac arrhythmias.