Intravenous magnesium sulphate and sotalol for prevention of atrial fibrillation after coronary artery bypass surgery: a systematic review and economic evaluation

Magnesium prophylaxis of new-onset atrial fibrillation: A systematic review and meta-analysis

PURPOSE

Atrial fibrillation (AF) is the most common cardiac arrhythmia in intensive care units (ICU) and is associated with increased morbidity and mortality. Magnesium prophylaxis has been shown to reduce incidence of AF in cardiac surgery patients, however, evidence outside this population is limited. The objective of this study is to summarize studies examining magnesium versus placebo in the prevention of NOAF outside the setting of cardiac surgery.

SOURCE

We performed a comprehensive search of MEDLINE, EMBASE, and Cochrane Library (CENTRAL) from inception until January 3rd, 2023. We included all interventional research studies that compared magnesium to placebo and excluded case reports and post cardiac surgery patients. We conducted meta-analysis using the inverse variance method with random effects modelling.

PRINCIPAL FINDINGS

Of the 1493 studies imported for screening, 87 full texts were assessed for eligibility and six citations, representing five randomized controlled trials (n = 4713), were included in the review, with four studies (n = 4654) included in the pooled analysis. Administration of magnesium did not significantly reduce the incidence of NOAF compared to placebo (OR 0.72, [95% CI 0.48 to 1.09]).

CONCLUSION

Use of magnesium did not reduce the incidence of NOAF, however these studies represent diverse groups and are hindered by significant bias. Further studies are necessary to determine if there is benefit to magnesium prophylaxis for NOAF in non-cardiac surgery patients.

Essential metals in health and disease

In total, twenty elements appear to be essential for the correct functioning of the human body, half of which are metals and half are non-metals. Among those metals that are currently considered to be essential for normal biological functioning are four main group elements, sodium (Na), potassium (K), magnesium (Mg), and calcium (Ca), and six d-block transition metal elements, manganese (Mn), iron (Fe), cobalt (Co), copper (Cu), zinc (Zn) and molybdenum (Mo). Cells have developed various metallo-regulatory mechanisms for maintaining a necessary homeostasis of metal-ions for diverse cellular processes, most importantly in the central nervous system. Since redox active transition metals (for example Fe and Cu) may participate in electron transfer reactions, their homeostasis must be carefully controlled. The catalytic behaviour of redox metals which have escaped control, e.g. via the Fenton reaction, results in the formation of reactive hydroxyl radicals, which may cause damage to DNA, proteins and membranes. Transition metals are integral parts of the active centers of numerous enzymes (e.g. Cu,Zn-SOD, Mn-SOD, Catalase) which catalyze chemical reactions at physiologically compatible rates. Either a deficiency, or an excess of essential metals may result in various disease states arising in an organism. Some typical ailments that are characterized by a disturbed homeostasis of redox active metals include neurological disorders (Alzheimer's, Parkinson's and Huntington's disorders), mental health problems, cardiovascular diseases, cancer, and diabetes. To comprehend more deeply the mechanisms by which essential metals, acting either alone or in combination, and/or through their interaction with non-essential metals (e.g. chromium) function in biological systems will require the application of a broader, more interdisciplinary approach than has mainly been used so far. It is clear that a stronger cooperation between bioinorganic chemists and biophysicists - who have already achieved great success in understanding the structure and role of metalloenzymes in living systems - with biologists, will access new avenues of research in the systems biology of metal ions. With this in mind, the present paper reviews selected chemical and biological aspects of metal ions and their possible interactions in living systems under normal and pathological conditions.

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.

Possibility of magnesium supplementation for supportive treatment in patients with COVID-19

Magnesium as an enzymatic activator is essential for various physiological functions such as cell cycle, metabolic regulation, muscle contraction, and vasomotor tone. A growing body of evidence supports that magnesium supplementation (mainly magnesium sulfate and magnesium oxide) prevents or treats various types of disorders or diseases related to respiratory system, reproductive system, nervous system, digestive system, and cardiovascular system as well as kidney injury, diabetes and cancer. The ongoing pandemic coronavirus disease 19 (COVID-19) characterized by respiratory tract symptoms with different degrees of important organ and tissue damages has attracted global attention. Particularly, effective drugs are still lacking in the COVID-19 therapy. In this review, we find and summarize the effectiveness of magnesium supplementation on the disorders or diseases, and provide a reference to the possibility of magnesium supplementation for supportive treatment in patients with COVID-19.

Effect of prophylaxis of magnesium sulfate for reduction of postcardiac surgery arrhythmia: Randomized clinical trial

BACKGROUND

Arrhythmia is a common complication after heart surgery and is a major source of morbidity and mortality.

AIMS

This study aimed to study the effect of magnesium sulfate (MgSO4) for reduction of postcardiac surgery arrhythmia.

SETTING AND DESIGN

This study is performed in the cardiac operating room and Intensive Care Unit (ICU) of Shahid Madani Hospital of Tabriz (Iran) between January 1, 2014, and September 30, 2014. This study is a double-blind, randomized controlled trial.

MATERIALS AND METHODS

In Group 1 (group magnesium [Mg]), eighty patients received 30 mg/kg MgSO4in 500 cc normal saline and in Group 2 (group control), eighty patients received 500 cc normal saline alone.

STATISTICAL ANALYSIS

The occurrence of arrhythmia was compared between groups by Chi-square and Fisher's exact test. In addition, surgical time, length of ICU stay, and length of hospital stay were compared by independent t-test. P< 0.05 was considered as significant.

RESULTS

There was a significant difference in the incidence of arrhythmia between two groups (P = 0.037). The length of ICU stay was 3.4 ± 1.4 and 3.73 ± 1.77 days in group MgSO4and control group, respectively, and there was no statistically significant difference between two groups (P = 0.2).

CONCLUSION

Mg significantly decreases the incidence of all type of postcardiac surgery arrhythmia and hospital length of stay at patients undergo cardiac surgery. We offer prophylactic administration of Mg at patients undergo cardiac surgery.

Does magnesium-supplemented cardioplegia reduce cardiac injury? A meta-analysis of randomized controlled trials

BACKGROUND

Magnesium is often used to supplement cardioplegic solutions during cardiopulmonary bypass due to its cardioprotective effect during ischemia and reperfusion. The aim of this meta-analysis was to evaluate the effects of magnesium-supplemented cardioplegia versus an inactive (placebo) control cardioplegia on reducing cardiac injury after cardiac arrest surgery, as found by randomized, controlled trials.

METHODS

The Medline, Cochrane Library, and Chinese literature databases (CJFD, CBM, CSJD, Wanfang) were comprehensively searched for reports of randomized, controlled trials (RCTs) evaluating magnesium-supplemented cardioplegic solutions. The clinical parameters and outcomes of interest were the incidence of postoperative low cardiac output, auto-rebeating rate, ICU stay length, new onset postoperative atrial fibrillation, peak value of CK-MB (and/or cTnI), incidence of myocardial infarction, and in-hospital mortality.

RESULTS

Ten trials, with a total of 1214 patients, were included. The frequency of low cardiac output, inotropic utilization, and myocardial infarction, as well as auto-rebeating rate, length of ICU stay and in-hospital mortality, were similar between the two groups. There was a marginal reduction in the incidence of new-onset postoperative atrial fibrillation in the magnesium-supplemented cardioplegia group.

CONCLUSIONS

The advantage of magnesium-supplemented cardioplegia, compared with cardioplegia without magnesium, remains unconvincing based on the current evidence. The decision to add magnesium to the cardioplegic solution to a patient undergoing cardiac arrest surgery should be carefully considered.

Magnesium physiology and clinical therapy in veterinary critical care

OBJECTIVE

To review magnesium physiology including absorption, excretion, and function within the body, causes of magnesium abnormalities, and the current applications of magnesium monitoring and therapy in people and animals.

ETIOLOGY

Magnesium plays a pivotal role in energy production and specific functions in every cell in the body. Disorders of magnesium can be correlated with severity of disease, length of hospital stay, and recovery of the septic patient. Hypermagnesemia is seen infrequently in people and animals with significant consequences reported. Hypomagnesemia is more common in critically ill people and animals, and can be associated with platelet, immune system, neurological, and cardiovascular dysfunction as well as alterations in insulin responsiveness and electrolyte imbalance.

DIAGNOSIS

Measurement of serum ionized magnesium in critically or chronically ill veterinary patients is practical and provides information necessary for stabilization and treatment. Tissue magnesium concentrations may be assessed using nuclear magnetic resonance spectroscopy as well as through the application of fluorescent dye techniques.

THERAPY

Magnesium infusions may play a therapeutic role in reperfusion injury, myocardial ischemia, cerebral infarcts, systemic inflammatory response syndromes, tetanus, digitalis toxicity, bronchospasms, hypercoagulable states, and as an adjunct to specific anesthetic or analgesic protocols. Further veterinary studies are needed to establish the frequency and importance of magnesium disorders in animals and the potential benefit of magnesium infusions as a therapeutic adjunct to specific diseases.

PROGNOSIS

The prognosis for most patients with magnesium disorders is variable and largely dependent on the underlying cause of the disorder.

Analgesic effect of magnesium in post-tonsillectomy patients: a prospective randomised clinical trial

The aim of this study was to assess the analgesic, bleeding and nausea/vomiting effects of magnesium with and without metamizol on post-tonsillectomy patients. This prospective and randomised clinical trial included 54 patients aged 18-63 years who were scheduled for elective tonsillectomy. The patients were randomly divided into two groups and administered either magnesium with metamizol or only metamizol. They had been classified as physical status class I and II using the American Society of Anesthesiologists guidelines. All patients underwent the same surgical procedure performed by a single surgeon. The groups did not differ according to age, sex, or duration of anaesthesia or surgery. Postoperative pain, bleeding and nausea/vomiting were evaluated using the VAS and bleeding and nausea/vomiting scores on the first, fifth and tenth days. On the first, fifth and tenth postoperative days, the VAS scores of the magnesium with metamizol group were significantly lower than those of the metamizol-only group (p1 = 0.001; p5 = 0.015; p10 = 0.015). There were no significant differences in postoperative bleeding and nausea/vomiting scores between the two groups (p = 0.425 and p = 0.258, respectively). This study showed that magnesium enhanced the analgesic effect on post-tonsillectomy pain. Use of magnesium with an analgesic drug may be beneficial for management of post-tonsillectomy pain.

Management strategies in cardiac surgery for postoperative atrial fibrillation: contemporary prophylaxis and futuristic anticoagulant possibilities

With more than a third of patients expected to endure the arrhythmia at any given time point, atrial fibrillation after cardiac surgery becomes a vexing problem in the postoperative care of cardiac surgery patients. The impact on patient care covers a spectrum from the more common clinically insignificant sequelae to debilitating embolic events. Despite this, postoperative atrial fibrillation generally masquerades as being insignificant, or at most as an anticipated inherent risk, merely extending one's hospital stay by a few days. As an independent risk factor for stroke, early and late mortality, and being a multibillion dollar strain on the healthcare system annually, postoperative atrial fibrillation is far more flagrant than a mere inherent risk. It is a serious medical quandary, which is not recognized as such. Though complete prevention is unrealistic, a step-wise treatment strategy that incorporates multiple preventative modalities can significantly reduce the impact of postoperative atrial fibrillation on patient care. The aims of this review are to present a brief overview of the arrhythmia's etiology, risk factors, and preventative strategies to reduce associated morbidities. Newer anticoagulants and the potential role of these drugs on future treatment paradigms are also discussed.

Magnesium adjunctive therapy in atrial arrhythmias

Magnesium (Mg) is an important intracellular ion with cardiac metabolism and electrophysiologic properties. A large percentage of patients with arrhythmias have an intracellular Mg deficiency, which is out of line with serum Mg concentrations, and this may explain the rationale for Mg's benefits as an atrial antiarrhythmic agent. A current limitation of antiarrhythmic therapy is that the potential for cardiac risk offsets some of the benefits of therapy. Mg enhances the balance of benefits to harms by enhancing atrial antiarrhythmic efficacy and reducing antiarrhythmic proarrhythmia potential as well as providing direct antiarrhythmic efficacy when used as monotherapy in patients undergoing cardiothoracic surgery.

Interventions for preventing post-operative atrial fibrillation in patients undergoing heart surgery

BACKGROUND

Atrial fibrillation is a common post-operative complication of cardiac surgery and is associated with an increased risk of post-operative stroke, increased length of intensive care unit and hospital stays, healthcare costs and mortality. Numerous trials have evaluated various pharmacological and non-pharmacological prophylactic interventions for their efficacy in preventing post-operative atrial fibrillation. We conducted an update to a 2004 Cochrane systematic review and meta-analysis of the literature to gain a better understanding of the effectiveness of these interventions.

OBJECTIVES

The primary objective was to assess the effects of pharmacological and non-pharmacological interventions for preventing post-operative atrial fibrillation or supraventricular tachycardia after cardiac surgery. Secondary objectives were to determine the effects on post-operative stroke or cerebrovascular accident, mortality, cardiovascular mortality, length of hospital stay and cost of treatment during the hospital stay.

SEARCH METHODS

We searched the Cochrane Central Register of ControlLed Trials (CENTRAL) (Issue 8, 2011), MEDLINE (from 1946 to July 2011), EMBASE (from 1974 to July 2011) and CINAHL (from 1981 to July 2011).

SELECTION CRITERIA

We selected randomized controlled trials (RCTs) that included adult patients undergoing cardiac surgery who were allocated to pharmacological or non-pharmacological interventions for the prevention of post-operative atrial fibrillation or supraventricular tachycardia, except digoxin, potassium (K(+)), or steroids.

DATA COLLECTION AND ANALYSIS

Two review authors independently abstracted study data and assessed trial quality.

MAIN RESULTS

One hundred and eighteen studies with 138 treatment groups and 17,364 participants were included in this review. Fifty-seven of these studies were included in the original version of this review while 61 were added, including 27 on interventions that were not considered in the original version. Interventions included amiodarone, beta-blockers, sotalol, magnesium, atrial pacing and posterior pericardiotomy. Each of the studied interventions significantly reduced the rate of post-operative atrial fibrillation after cardiac surgery compared with a control. Beta-blockers (odds ratio (OR) 0.33; 95% confidence interval) CI 0.26 to 0.43; I(2) = 55%) and sotalol (OR 0.34; 95% CI 0.26 to 0.43; I(2) = 3%) appear to have similar efficacy while magnesium's efficacy (OR 0.55; 95% CI 0.41 to 0.73; I(2) = 51%) may be slightly less. Amiodarone (OR 0.43; 95% CI 0.34 to 0.54; I(2) = 63%), atrial pacing (OR 0.47; 95% CI 0.36 to 0.61; I(2) = 50%) and posterior pericardiotomy (OR 0.35; 95% CI 0.18 to 0.67; I(2) = 66%) were all found to be effective. Prophylactic intervention decreased the hospital length of stay by approximately two-thirds of a day and decreased the cost of hospital treatment by roughly $1250 US. Intervention was also found to reduce the odds of post-operative stroke, though this reduction did not reach statistical significance (OR 0.69; 95% CI 0.47 to 1.01; I(2) = 0%). No significant effect on all-cause or cardiovascular mortality was demonstrated.

AUTHORS' CONCLUSIONS

Prophylaxis to prevent atrial fibrillation after cardiac surgery with any of the studied pharmacological or non-pharmacological interventions may be favored because of its reduction in the rate of atrial fibrillation, decrease in the length of stay and cost of hospital treatment and a possible decrease in the rate of stroke. However, this review is limited by the quality of the available data and heterogeneity between the included studies. Selection of appropriate interventions may depend on the individual patient situation and should take into consideration adverse effects and the cost associated with each approach.

Treatment of hypertension in patients undergoing coronary artery by-pass grafting

Hypertension occurs in up to 80% of patients scheduled to coronary artery by-pass grafting (CABG). In hemodynamically stable patients all anti-hypertensive drugs should be continued till a day of surgery. For vast majority of patients there is no need to use blood pressure lowering agents during CABG, however it is necessary to maintain blood pressure level and avoid extreme blood pressure variations. Upon CABG hypotensive therapy should be modified to the needs of the individual patient and should be monitored individually. Treatment of hypertension ought to be started with caution with lowest possible dosage. Aggressive therapy is strongly discouraged to avoid hemodynamic collapse. Beta-blockers should be administered to all CABG patients unless contraindicated.

Warm-blood cardioplegia with low or high magnesium for coronary bypass surgery: a randomised controlled trial

Objective: Magnesium (Mg²⁺) is cardioprotective and has been routinely used to supplement cardioplegic solutions during coronary artery bypass graft (CABG) surgery. However, there is no consensus about the Mg²⁺ concentration that should be used. The aim of this study was to compare the effects of intermittent antegrade warm-blood cardioplegia supplemented with either low- or high-concentration Mg²⁺. Methods: This study was a randomised controlled trial carried out in two cardiac surgery centres, Bristol, UK and Cuneo, Italy. Patients undergoing isolated CABG with cardiopulmonary bypass were eligible. Patients were randomised to receive warm-blood cardioplegia supplemented with 5 or 16 mmol l⁻¹ Mg²⁺. The primary outcome was postoperative atrial fibrillation. Secondary outcomes were serum biochemical markers (troponin I, Mg²⁺, potassium, lactate and creatinine) and time-to-plegia arrest. Intra-operative and postoperative clinical outcomes were also recorded. Results: Data from two centres for 691 patients (342 low and 349 high Mg²⁺) were analysed. Baseline characteristics were similar for both groups. There was no significant difference in the frequency of postoperative atrial fibrillation in the high (32.8%) and low (32.0%) groups (risk ratio 1.03, 95% confidence interval, CI, 0.82–1.28). However, compared with the low group, troponin I release was 28% less (95% CI 55–94%, p = 0.02) in the high-Mg²⁺ group. The 30-day mortality was 0.72% (n = 5); all deaths occurred in the high-Mg²⁺ group but there was no significant difference between the groups (p = 0.06). Frequencies of other major complications were similar in the two groups. Conclusions: Warm-blood cardioplegia supplemented with 16 mmol l⁻¹ Mg²⁺, compared with 5 mmol l⁻¹ Mg²⁺, does not reduce the frequency of postoperative atrial fibrillation in patients undergoing CABG but may reduce cardiac injury. (This trial was registered as ISRCTN95530505.)

Trial design: Computer guided normal-low versus normal-high potassium control in critically ill patients: Rationale of the GRIP-COMPASS study

Background

Potassium depletion is common in hospitalized patients and can cause serious complications such as cardiac arrhythmias. In the intensive care unit (ICU) the majority of patients require potassium suppletion. However, there are no data regarding the optimal control target in critically ill patients. After open-heart surgery, patients have a strongly increased risk of atrial fibrillation or atrial flutter (AFF). In a novel trial design, we examined if in these patients different potassium control-targets within the normal range may have different effects on the incidence of AFF.

Methods/Design

The "computer-driven Glucose and potassium Regulation program in Intensive care Patients with COMparison of PotASSium targets within normokalemic range (GRIP-COMPASS) trial" is a single-center prospective trial in which a total of 1200 patients are assigned to either a potassium control-target of 4.0 mmol/L or 4.5 mmol/L in consecutive alternating blocks of 50 patients each. Potassium levels are regulated by the computer-assisted potassium suppletion algorithm called GRIP-II (Glucose and potassium regulation for Intensive care Patients). Primary endpoint is the in-hospital incidence of AFF after cardiac surgery. Secondary endpoints are: in-hospital AFF in medical patients or patients after non-cardiac surgery, actually achieved potassium levels and their variation, electrolyte and glucose levels, potassium and insulin requirements, cumulative fluid balance, (ICU) length of stay, ICU mortality, hospital mortality and 90-day mortality.

Discussion

The GRIP-COMPASS trial is the first controlled clinical trial to date that compares potassium targets. Other novel methodological elements of the study are that it is performed in ICU patients where both targets are within the normal range and that a computer-assisted potassium suppletion algorithm is used.

Trial registration

NCT 01085071 at ClinicalTrials.gov

Is There a Future for Neuroprotective Agents in Cardiac Surgery?

This article gives an overview of neuroprotective drugs that were recently tested in clinical trials in cardiac surgery. Also, recommendations are given for successful translational research and considerations for management during cardiac surgery.

Biatrial pacing vs. intravenous amiodarone in prevention of atrial fibrillation after coronary artery bypass surgery

This study was aimed to compare the results of post operative biatrial pacing and i.v. amiodarone in prevention of AF. In a single blind randomized clinical trial, 210 patients scheduled for elective CABG surgery were randomized either to receive overdrive biatrial pacing, i.v. amiodarone or no intervention. Incidence of AF postoperatively evaluated. Pacing was successful in 83% of patients and 80% of patients in amiodarone group could receive their drug. Twenty and one patients developed AF. Incidence of AF in pace, amiodarone and control group was 10.7, 5.3 and 17.9%, respectively (p = 0.08). Comparing incidence of AF between pacing and control group, the difference was not significant (p = 0.2), but the difference between amiodarone and control groups was significant statistically (p = 0.03). Patients who developed AF were older but their left ventricular ejection fraction was not different with patients without AF. The ICU stay was higher in patients with AF. Use of i.v. amiodarone was more effective than biatrial pacing in prevention of post operative AF and we recommend use of this drug in high risk patients.