Intravenous amiodarone or magnesium sulphate is not cost-beneficial prophylaxis for atrial fibrillation after coronary artery bypass surgery

Evaluation of the effect of small single intravenous dose of amiodarone on the prevention of arrhythmias in patients who underwent coronary artery bypass graft surgery: A randomized controlled trial

Background

Atrial fibrillation (AF) is the most frequent arrhythmia after cardiac surgery causing a range of clinical symptoms and treatments that develop in around one-third of coronary artery bypass surgery patients. We aimed to evaluate the effect of Amiodarone in preventing arrhythmia in patients undergoing coronary artery bypass surgery.

Method

In this double-blind randomized clinical trial, 60 patients candidate for coronary artery bypass surgery above the age of 18 were included and randomly divided into two groups of intervention, receiving an infusion of Amiodarone (3 mg/kg) 10 min (in 100 cc Normal saline) before declamping of the aorta, and a control group, receiving 100 cc of saline 10 min before declamping of the aorta. The patient's demographic, clinical features, and hospital and clinical course were recorded.

Results

After undergoing operation, 22 (36.67%) of patients were developed arrhythmia. The Amiodarone group demonstrated significantly lower reperfusion ventricular fibrillation (RVF) rates (26.7% vs. 70%; p = .001) and AF occurrence (13.3% vs. 60%; p < .001) during the initial 24 h after surgery compared to the placebo group. There was no significant difference between the two groups regarding the need for D/C shock after removing the aortic clamp. (p = .117) Furthermore, the intensive care unit stay among the amiodaron group was significantly lower than the control group (2.43 vs. 3.07 days; p = .013).

Conclusion

The predictive properties in the administration of single intravenous low-dose Amiodarone 10 min before the declamping of the aorta can significantly lower the rates of RVF and AF after coronary artery bypass grafting, while also decreasing hospitalization duration.

Prevention of Atrial Fibrillation After Cardiac Surgery: A Review of Literature and Comparison of Different Treatment Modalities

Atrial fibrillation is the most common arrhythmia to occur after cardiac surgery, with an incidence of 10% to 50%. It is associated with postoperative complications including increased risk of stroke, prolonged hospital stays and increased costs. Despite new insights into the mechanisms of atrial fibrillation, no specific etiologic factor has been identified as the sole perpetrator of the arrhythmia. Current evidence suggests that the pathophysiology of atrial fibrillation in general, as well as after cardiac surgery, is multifactorial. Studies have also shown that new-onset postoperative atrial fibrillation following cardiac surgery is associated with a higher risk of short-term and long-term mortality. Furthermore, it has been demonstrated that prophylactic medical therapy decreases the incidence of postoperative atrial fibrillation after cardiac surgery. Of note, the incidence of postoperative atrial fibrillation has not changed during the last decades despite the numerous preventive strategies and operative techniques proposed, although the perioperative and postoperative care of cardiac patients as such has improved.

Navigating the Incidence of Postoperative Arrhythmia and Hospitalization Length: The Role of Amiodarone and Other Antiarrhythmics in Prophylaxis

Antiarrhythmic drugs play a pivotal role in managing and preventing arrhythmias. Amiodarone, classified as a class III antiarrhythmic, has been used prophylactically to effectively prevent atrial fibrillation postoperatively in cardiac surgeries. However, there is a lack of consensus on the use of amiodarone and other antiarrhythmic drugs as prophylaxis to reduce the occurrence of all types of postoperative arrhythmias in cardiac and non-cardiac surgeries. A comprehensive PubMed query yielded 614 relevant papers, of which 52 clinical trials were analyzed. The data collection included the class of antiarrhythmics, timing or method of drug administration, surgery type, type of arrhythmia and its incidence, and hospitalization length. Statistical analyses focused on prophylactic antiarrhythmics and their respective reductions in postoperative arrhythmias and hospitalization length. Prophylactic amiodarone alone compared to placebo demonstrated a significant reduction in postoperative arrhythmia incidence in cardiac and non-cardiac surgeries (24.01%, p<0.0001), and it was the only treatment group to significantly reduce hospitalization length versus placebo (p = 0.0441). Prophylactic use of class 4 antiarrhythmics versus placebo also demonstrated a significant reduction in postoperative arrhythmia incidence (28.01%, p<0.0001), and while there was no significant statistical reduction compared to amiodarone (4%, p=0.9941), a lack of abundant data provides a case for further research on the prophylactic use of class 4 antiarrhythmics for this indication. Amiodarone prophylaxis remains a prime cornerstone of therapy in reducing postoperative arrhythmia incidence and hospitalization length. Emerging data suggests a need for a broader exploration of alternative antiarrhythmic agents and combination therapies, particularly class 4 antiarrhythmics, in both cardiac and non-cardiac surgeries. This meta-analysis depicts the effectiveness of amiodarone, among other antiarrhythmics, in postoperative arrhythmia incidence and hospitalization length reduction in cardiac and non-cardiac surgeries.

Combination prophylactic amiodarone with beta-blockers versus beta-blockers in atrial fibrillation after cardiac surgery: A systematic-review and meta-analysis

BACKGROUND

Guideline recommendations regarding the preferred preventive measures for postoperative atrial fibrillation (POAF) are unclear, nor have we found any review articles addressing the combination of amiodarone and beta-blockers for the prevention of POAF.

OBJECTIVES

To investigate the efficacy and safety of combination beta-blockers and amiodarone in the prevention of POAF while also comparing the use of amiodarone and beta-blockers individually.

METHODS

We used Pubmed as the primary resource. POAF incidence was the primary outcome of this study. The secondary outcomes were hospital length of stay (LOS), ICU LOS, treatment-related drug discontinuation (TRDD), and mortality. The random-effects model assessed all pooled outcomes with 95% confidence intervals. Statistical significance was set at p≤0.05.

RESULTS

The amiodarone subgroup of POAF incidence saw a Risk Ratio (RR) of 0.81 [0.63, 1.06], p=0.12, while the combination subgroup resulted in a RR of 0.63 [0.49, 0.80], p <0.001. TRDD for the amiodarone subgroup resulted in a RR of 0.68 [0.25, 1.82], p=0.44, while the combination subgroup saw a RR of 0.84 [0.57, 1.23], p=0.36. For mortality, the amiodarone subgroup resulted in a RR of 0.97 [0.48, 1.98], p=0.93, while the combination subgroup resulted in a RR of 1.04 [0.27, 4.05], p=0.96. Both hospital and ICU LOS saw no significant difference between treatment arms for both the combination subgroup and amiodarone alone. Except for the incidence of postoperative atrial fibrillation (POAF) in the combination prophylaxis group, most of the measured outcomes did not meet the optimized information size (OIS) that was estimated.

CONCLUSION

Combination prophylaxis with amiodarone and beta-blockers significantly lowered risks of POAF incidence in comparison to beta-blockers alone while also having comparative mortality and TRDD outcomes.

Postoperative Atrial Fibrillation Following Cardiac Surgery: From Pathogenesis to Potential Therapies

Postoperative atrial fibrillation (POAF) is a major complication after cardiac surgery which can lead to high rates of morbidity and mortality, an enhanced length of hospital stay, and an increased cost of care. POAF is postulated to be a multifactorial phenomenon; however, some major pathogeneses have been proposed, including inflammatory pathways, oxidative stress, and autonomic dysfunction. Genetic studies also showed that inflammatory pathways, beta-1 adrenoreceptor variants, G protein-coupled receptor kinase 5 gene variants, and non-coding single-nucleotide polymorphisms in the 4q25 chromosomal locus are involved in this phenomenon. Moreover, several predisposing factors lead to the development of POAF, consisting of pre-, intra-, and postoperative contributors. The main predisposing factors comprise age, prior history of major cardiovascular risk factors, and ischemia-reperfusion injury during surgery. The management of POAF is based on the usual therapies used for non-surgical AF, including medications for either rate control or rhythm control in hemodynamically unstable patients. The perioperative administration of β-blockers and some antiarrhythmic agents has been recommended in major international guidelines. In addition, upstream therapies consisting of colchicine, magnesium, statins, and antioxidants have attenuated the incidence of POAF; however, some uncomfortable side effects developed in large randomized trials. The use of anticoagulation has also resulted in less mortality in patients with POAF at higher risk of thromboembolic events. Despite these recommendations, the actual regimen for the prevention of POAF remains controversial. In this review, we highlight the pathogenesis, predisposing factors, and potential therapeutic options for the management of patients at risk for or with POAF following cardiac surgery.

Role of Prophylactic Magnesium Supplementation in Prevention of Postoperative Atrial Fibrillation in Patients Undergoing Coronary Artery Bypass Grafting: a Systematic Review and Meta-Analysis of 20 Randomized Controlled Trials

Background

Several randomized trials have evaluated the efficacy of prophylactic magnesium (Mg) supplementation in prevention of post-operative atrial fibrillation (POAF) in patients undergoing cardiac artery bypass grafting (CABG). We aimed to determine the role of prophylactic Mg in 3 different settings (intraoperative, postoperative, intraoperative plus postoperative) in prevention of POAF.

Methods

A systemic literature search was performed (until January 19, 2019) using PubMed, EMBASE, Web of Science, and Cochrane Central Register of Controlled Trials to identify trials evaluating Mg supplementation post CABG. Primary outcome of our study was reduction in POAF post CABG.

Results

We included a total of 2,430 participants (1,196 in the Mg group and 1,234 in the placebo group) enrolled in 20 randomized controlled trials. Pooled analysis demonstrated no reduction in POAF between the two groups (RR 0.90; 95% CI, 0.79-1.03; p=0.13; I2=42.9%). In subgroup analysis, significant reduction in POAF was observed with postoperative Mg supplementation (RR 0.76; 95% CI, 0.58-0.99; p=0.04; I2=17.6%) but not with intraoperative or intraoperative plus postoperative Mg supplementation (RR 0.77; 95% CI, 0.49-1.22; p = 0.27; I2=49% and RR 0.92; 95% CI, 0.68-1.24; p = 0.58; I2=51.8%, respectively).

Conclusions

Magnesium supplementation, especially in the postoperative period, is an effective strategy in reducing POAF following CABG.

Magnesium sulphate replacement therapy in cardiac surgery patients: A systematic review

OBJECTIVE

The objective of this review was to identify evidence to inform clinical practice guidelines for magnesium sulphate (MgSO₄) replacement therapy for postoperative cardiac surgery patients.

DATA SOURCES

Three databases were systematically searched: CINAHL Complete, MEDLINE Complete, and EmBase.

REVIEW METHOD USED

A systematic literature review method was used to locate, appraise, and synthesise available evidence for each step of the medication management cycle (indication, prescription, preparation, administration, and monitoring) for MgSO₄ replacement therapy. Database searches used combinations of synonyms for postoperation or surgery, cardiac, heart, arrhythmia, atrial fibrillation, and magnesium sulphate. Search results were independently screened for inclusion by two researchers at title, abstract, and full-text stages with good statistical agreement (kappa scores of 0.99, 0.87, and 1.00, respectively).

RESULTS

Twenty-four included studies reported varying methodologies, data collected, and medication management practices. Of these, 23 studies (95.8%) excluded patients with comorbidities commonly observed in clinical practice. This review identified low-level evidence for two practice recommendations: (i) concurrent administration of MgSO₄ with medications recommended as the best practice for prevention of postoperative atrial fibrillation and (ii) clinical and laboratory monitoring of magnesium blood serum levels, vital signs, and electrocardiography should be performed during MgSO₄ replacement therapy. Evidence to inform MgSO₄ replacement therapy for each medication management cycle step was limited; therefore, a guideline could not be developed.

CONCLUSIONS

Although MgSO₄ is routinely administered to prevent hypomagnesaemia in postoperative cardiac surgery patients, there was insufficient evidence to guide critical care nurses in each medication management cycle step for MgSO₄ replacement therapy. These findings precluded the development of comprehensive recommendations to standardise this practice. Poor standardisation can increase the risk for patient harm related to variation in clinical processes and procedural errors. In light of this evidence gap, consensus of expert opinion should be used as a strategy to guide MgSO₄ medication management.

Evaluating the effect of magnesium supplementation and cardiac arrhythmias after acute coronary syndrome: a systematic review and meta-analysis

BACKGROUND

Atrial and ventricular cardiac arrhythmias are one of the most common early complications after cardiac surgery and these serve as a major cause of mortality and morbidity after cardiac revascularization. We want to evaluate the effect of magnesium sulfate administration on the incidence of cardiac arrhythmias after cardiac revascularization by doing this systematic review and meta-analysis.

METHODS

The search performed in several databases (SID, Magiran, IranDoc, IranMedex, MedLib, PubMed, EmBase, Web of Science, Scopus, the Cochrane Library and Google Scholar) for published Randomized controlled trials before December 2017 that have reported the association between Magnesium consumption and the incidence of cardiac arrhythmias. This relationship measured using odds ratios (ORs) with a confidence interval of 95% (CIs). Funnel plots and Egger test used to examine publication bias. STATA (version 11.1) used for all analyses.

RESULTS

Twenty-two studies selected as eligible for this research and included in the final analysis. The total rate of ventricular arrhythmia was lower in the group receiving magnesium sulfate than placebo (11.88% versus 24.24%). The same trend obtained for the total incidence of supraventricular arrhythmia (10.36% in the magnesium versus 23.91% in the placebo group). In general the present meta-analysis showed that magnesium could decrease ventricular and supraventricular arrhythmias compared with placebo (OR = 0.32, 95% CI 0.16-0.49; p < 0.001 and OR = 0.42, 95% CI 0.22-0.65; p < 0.001, respectively). Subgroup analysis showed that the effect of magnesium on the incidence of cardiac arrhythmias was not affected by clinical settings and dosage of magnesium. Meta-regression analysis also showed that there was no significant association between the reduction of ventricular arrhythmias and sample size.

CONCLUSION

The results of this meta-analysis study suggest that magnesium sulfate can be used safely and effectively and is a cost-effective way in the prevention of many of ventricular and supraventricular arrhythmias.

Magnesium status and magnesium therapy in cardiac surgery: A systematic review and meta-analysis focusing on arrhythmia prevention

PURPOSE

To investigate magnesium as prophylaxis or treatment of postoperative arrhythmias in cardiac surgery (CS) patients. To assess impact on biochemical and patient-centered outcomes.

MATERIALS AND METHODS

We searched MEDLINE, CENTRAL and EMBASE electronic databases from 1975 to October 2015 using terms related to magnesium and CS. English-Language RCTs were included involving adults undergoing CS with parenterally administered magnesium to treat or prevent arrhythmias, compared to control or standard antiarrythmics. We extracted incidence of postoperative arrhythmias, termination following magnesium administration and secondary outcomes (including mortality, length of stay, hemodynamic parameters, biochemistry).

RESULTS

Thirty-five studies were included, with significant methodological heterogeneity. Atrial fibrillation (AF) was most commonly reported, followed by ventricular, supraventricular and overall arrhythmia frequency. Magnesium appeared to reduce AF (RR 0.69, 95% confidence interval (95%CI) 0.56-0.86, p=0.002), particularly postoperatively (RR 0.51, 95%CI 0.34-0.77, p=0.003) for longer than 24h. Maximal benefit was seen with bolus doses up to 60mmol. Magnesium appeared to reduce ventricular arrhythmias (RR=0.46, 95%CI 0.24-0.89, p=0.004), with a trend to reduced overall arrhythmias (RR=0.80, 95%CI 0.57-1.12, p=0.191). We found no mortality effect or significant increase in adverse events.

CONCLUSIONS

Magnesium administration post-CS appears to reduce AF without significant adverse events. There is limited evidence to support magnesium administration for prevention of other arrhythmias.

The role of magnesium sulfate in the intensive care unit

Magnesium (Mg) has been developed as a drug with various clinical uses. Mg is a key cation in physiological processes, and the homeostasis of this cation is crucial for the normal function of body organs. Magnesium sulfate (MgSO4) is a mineral pharmaceutical preparation of magnesium that is used as a neuroprotective agent. One rationale for the frequent use of MgSO4 in critical care is the high incidence of hypomagnesaemia in intensive care unit (ICU) patients. Correction of hypomagnesaemia along with the neuroprotective properties of MgSO4 has generated a wide application for MgSO4 in ICU.

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.

Postoperative atrial fibrillation in patients with left atrial myxoma

Introduction

The aim of this study was to determine the factors associated with postoperative atrial fibrillation (AF) in patients with left atrial (LA) myxoma.

Methods

Thirty-six consecutive patients with LA myxoma (10 men, mean age: 49.3 ± 15.7 years), who were operated on between March 2010 and July 2012, were included in this retrospective study. Pre-operative electrocardiograms and echocardiographic examinations of each patient were reviewed.

Results

Postoperative AF developed in 10 patients, whereas there was no evidence of paroxysmal AF after resection of the LA myxoma in the remaining 26 patients. The patients who developed AF postoperatively were significantly older than those who did not develop AF (median: 61.5 vs 46 years; p = 0.009). Among the electrocardiographic parameters, only P-wave dispersion differed significantly between postoperative AF and non-AF patients (median: 57.6 vs 39.8 ms, p = 0.004). Logistic regression analysis revealed P-wave dispersion (OR: 1.11, 95% CI: 1.003–1.224, p = 0.043) and age (OR: 1.13, 95% CI: 1.001–1.278, p = 0.048) as independent predictors of postoperative AF in our cohort of patients.

Conclusions

P-wave dispersion is a simple and useful parameter for the prediction of postoperative AF in patients with LA myxoma.

Pharmacological strategies for prevention of postoperative atrial fibrillation

Atrial fibrillation (AF) complicating cardiac surgery continues to be a major problem that increases the postoperative risk of stroke, myocardial infarction, heart failure and costs and can affect long-term survival. The incidence of AF after surgery has not significantly changed over the last two decades, despite improvement in medical and surgical techniques. The mechanism and pathophysiology underlying postoperative AF (PoAF) is incompletely understood and results from a combination of acute and chronic factors, superimposed on an underlying abnormal atrial substrate with increased interstitial fibrosis. Several anti-arrhythmic and non-anti-arrhythmic medications have been used for the prevention of PoAF, but the effectiveness of these strategies has been limited due to a poor understanding of the basis for the increased susceptibility of the atria to AF in the postoperative setting. In this review, we summarize the pathophysiology underlying the development of PoAF and evidence behind pharmacological approaches used for its prevention in the postoperative setting.

Levosimendan Use Decreases Atrial Fibrillation in Patients after Coronary Artery Bypass Grafting: A Pilot Study

Background: Atrial fibrillation (AF) often occurs after coronary artery bypass grafting (CABG) and can result in increased morbidity and mortality due to complications. In the present study, our goal was to investigate whether the use of levosimendan can reduce the frequency of AF after coronary artery bypass grafting in patients with poor left ventricle function. Material and Methods: To investigate the effectiveness of levosimendan in the prophylaxis of AF, we conducted a prospective, randomized, placebo-controlled clinical study on 200 consecutive patients in whom we performed elective CABG operations. Baseline characteristics were similar in both groups. A control group of 100 patients were treated with placebo (500 mL saline solution), whereas the levosimendan group (n = 100 patients) was treated with levosimendan. High-sensitivity C-reactive protein, cardiac troponin, and creatine kinase–MB levels were measured before surgery and 5 days postoperatively. Results: AF occurred in 12% of the levosimendan group and 36% of the control group. The occurrence of AF was significantly lower in the levosimendan group (P < 0.05). The duration of AF in the levosimendan group was significantly shorter than that in the control group (4.83 ± 1.12 and 6.50 ± 1.55 hours, respectively; P = 0.028). Our research showed that C-reactive protein was higher postoperatively in the control group than in the levosimendan group (P < 0.05). Conclusions: The incidence of postoperative AF in the levosimendan group was reduced significantly in patients with poor left ventricle function after CABG operations.

Investigating the relationship between intra-operative electrolyte abnormalities (sodium and potassium) with post-operative complications of coronary artery bypass surgery

Background:

Generally, the electrolyte abnormalities are seen in many hospitalized patients, and this problem increases in ones with heart diseases. The purpose of this study is determination of the prevalence of electrolyte abnormalities during the coronary artery bypass surgery (CABG) and detecting the relationship between these abnormalities with the complications after the surgeries.

Materials and Methods:

This is a cross-sectional study, which is done in Chamran hospital, the medical and educational center of Isfahan, Iran, in 2011. The target population included the patients who have undergone CABG in this hospital. In this study, 100 patients who had been candidates for CABG were selected, and we extracted their recorded intra-operative electrolyte information. The collected data was entered into the computer and analyzed by SPSS software. The Chi-square and t student tests were used for data analysis.

Results:

The mean ± SD of sodium during CABG was 137.95 ± 4.6 (range 127-152) mg\dl. Also, the mean ± SD of potassium was 4.65 ± 0.9 (range: 2.9-7.4). According to these results, 48 patients (48% of all) had electrolyte imbalance and 52 patients (52% of all) were normal. Sodium level in 71% of patients was normal, and in 29% of them was abnormal. Potassium level in 73% of individuals was normal, and in 27% of them was abnormal.

Conclusion:

Giving an attention to electrolyte abnormalities in patients who have undergone CABG surgery is a considerable necessity for them, and sufficient arrangements are needed to prevent such abnormalities.

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.

Meta-analysis of randomized controlled trials on magnesium in addition to beta-blocker for prevention of postoperative atrial arrhythmias after coronary artery bypass grafting

Background

Atrial arrhythmia (AA) is the most common complication after coronary artery bypass grafting (CABG). Only beta-blockers and amiodarone have been convincingly shown to decrease its incidence. The effectiveness of magnesium on this complication is still controversial. This meta-analysis was performed to evaluate the effect of magnesium as a sole or adjuvant agent in addition to beta-blocker on suppressing postoperative AA after CABG.

Methods

We searched the PubMed, Medline, ISI Web of Knowledge, Cochrane library databases and online clinical trial database up to May 2012. We used random effects model when there was significant heterogeneity between trials and fixed effects model when heterogeneity was negligible.

Results

Five randomized controlled trials were identified, enrolling a total of 1251 patients. The combination of magnesium and beta-blocker did not significantly decrease the incidence of postoperative AA after CABG versus beta-blocker alone (odds ratio (OR) 1.12, 95% confidence interval (CI) 0.86-1.47, P = 0.40). Magnesium in addition to beta-blocker did not significantly affect LOS (weighted mean difference −0.14 days of stay, 95% CI −0.58 to 0.29, P = 0.24) or the overall mortality (OR 0.59, 95% CI 0.08-4.56, P = 0.62). However the risk of postoperative adverse events was higher in the combination of magnesium and beta-blocker group than beta-blocker alone (OR 2.80, 95% CI 1.66-4.71, P = 0.0001).

Conclusions

This meta-analysis offers the more definitive evidence against the prophylactic administration of intravenous magnesium for prevention of AA after CABG when beta-blockers are routinely administered, and shows an association with more adverse events in those people who received magnesium.

Intravenous magnesium prevents atrial fibrillation after coronary artery bypass grafting: a meta-analysis of 7 double-blind, placebo-controlled, randomized clinical trials

Background

Postoperative atrial fibrillation (POAF) is the most common complication after coronary artery bypass grafting (CABG). The preventive effect of magnesium on POAF is not well known. This meta-analysis was undertaken to assess the efficacy of intravenous magnesium on the prevention of POAF after CABG.

Methods

Eligible studies were identified from electronic databases (Medline, Embase, and the Cochrane Library). The primary outcome measure was the incidence of POAF. The meta-analysis was performed with the fixed-effect model or random-effect model according to heterogeneity.

Results

Seven double-blind, placebo-controlled, randomized clinical trials met the inclusion criteria including 1,028 participants. The pooled results showed that intravenous magnesium reduced the incidence of POAF by 36% (RR 0.64; 95% confidence interval (CI) 0.50-0.83; P = 0.001; with no heterogeneity between trials (heterogeneity P = 0.8, I² = 0%)).

Conclusions

This meta-analysis indicates that intravenous magnesium significantly reduces the incidence of POAF after CABG. This finding encourages the use of intravenous magnesium as an alternative to prevent POAF after CABG. But more high quality randomized clinical trials are still need to confirm the safety.

Examining the safety of amiodarone

INTRODUCTION

Amiodarone is the most widely used antiarrhythmic agent, with demonstrated effectiveness against all the spectrum of cardiac tachyarrhythmias. The risk of adverse effects acts as a limiting factor to its utilization especially in the long term. This article systematically reviews the published evidence on amiodarone versus placebo to examine its safety as an antiarrhythmic drug.

AREAS COVERED

Authors collected data on adverse effects reported in 49 randomized placebo-controlled trials with amiodarone. Adverse effects were classified according to the organ/system involved. Pooled estimates of the number needed to treat (NNT) and to harm (NNH) versus placebo were calculated.

EXPERT OPINION

Amiodarone is effective for both the acute conversion of atrial fibrillation (AF) (11 trials, NNT = 4 at 24 h; p = 0.003) and the prevention of postoperative AF (18 trials, NNT = 8; p < 0.001), although with an increased risk of bradycardia, hypotension, nausea or phlebitis (pooled NNH = 4; p < 0.001). Amiodarone administration for the maintenance of sinus rhythm has a favorable net clinical benefit (pooled NNT = 3; p < 0.001 versus pooled NNH for either thyroid toxicity, gastrointestinal discomfort, skin toxicity or eye toxicity = 11; p < 0.001). Treatment with amiodarone for the prophylaxis of sudden cardiac death has less favorable net clinical benefit (15 trials, NNT = 38; p < 0.001 versus NNH for either thyroid toxicity, hepatic toxicity, pulmonary toxicity or bradycardia = 14; p < 0.001). Amiodarone treatment in this setting should be used in only selected cases.

Prophylaxis against atrial fibrillation after cardiac surgery: effective, but not routinely used--a survey of cardiothoracic units in the United kingdom

OBJECTIVE

To establish whether international recommendations on chemoprophylaxis against postoperative atrial fibrillation in cardiac surgery patients are implemented locally in cardiothoracic units in the United Kingdom; to determine which drugs are being used, how long they are given, and whether outcomes are monitored.

DESIGN

Survey of local cardiothoracic center guidelines.

SETTING

Postal and telephone survey.

PARTICIPANTS

Senior anesthesiologists and critical care staff in all 37 public cardiothoracic units in the United Kingdom.

INTERVENTION

None.

MEASUREMENTS AND MAIN RESULTS

Results were obtained from all contacted cardiothoracic units. Five units (14%) have local guidelines for chemoprophylaxis against atrial fibrillation in place. All use β-antagonists as their primary prophylactic drugs; only one unit uses amiodarone as a secondary prophylactic drug. Duration of prophylactic treatment varies, from 5 days to 6 weeks postoperatively. Thirty-two units (86%) have no local guidelines for chemoprophylaxis in place.

CONCLUSION

Chemoprophylaxis against postoperative atrial fibrillation in cardiac surgery patients remains underused, despite its effectiveness and recommendations for its routine use by several international organizations. Departmental guidelines help to ensure routine use, but this survey shows that so far only a minority of cardiothoracic units in the United Kingdom have implemented such guidelines. Awareness of the advantages of routine prophylaxis against atrial fibrillation should be improved and departmental prescribing policies encouraged.

Pharmacologic prophylaxis for atrial fibrillation following cardiac surgery: a systematic review

Atrial Fibrillation (AF) is the most common arrhythmia occurring after cardiac surgery. Its incidence varies depending on type of surgery. Postoperative AF may cause hemodynamic deterioration, predispose to stroke and increase mortality. Effective treatment for prophylaxis of postoperative AF is vital as reduces hospitalization and overall morbidity. Beta-blockers, have been proved to prevent effectively atrial fibrillation following cardiac surgery and should be routinely used if there are no contraindications. Sotalol may be more effective than standard b-blockers for the prevention of AF without causing an excess of side effects. Amiodarone is useful when beta-blocker therapy is not possible or as additional prophylaxis in high risk patients. Other agents such as magnesium, calcium channels blocker or non-antiarrhythmic drugs as glycose-insulin--potassium, non-steroidal anti-inflammatory drugs, corticosteroids, N-acetylcysteine and statins have been studied as alternative treatment for postoperative AF prophylaxis.

Atorvastatin for reduction of myocardial dysrhythmia after cardiac surgery study

Evaluation of: Patti G, Chello M, Candura D et al.: Atorvastatin for Reduction of MYocardial Dysrhythmia After cardiac surgery (ARMYDA-3) study. Circulation 114, 1455-1461 (2006). The Atorvastatin for Reduction of MYocardial Dysrhythmia After cardiac surgery study evaluated the efficacy of atorvastatin 40 mg/day compared with placebo, adminstered 1 week prior to surgery in preventing post-operative atrial fibrillation (AF). The rate of post-operative AF and mean post-operative hospital stay was significantly lower in the atorvastatin group compared with the placebo group. The incidence of the composite end point at 1 month was similar in both groups. This study supports the initiation of atorvastatin in patients undergoing cardiac surgery to reduce the rate of post-operative AF and the duration of hospital stay. Future studies will be required to assess whether this beneficial effect of atorvastatin is demonstrated by all statins and whether it can be extended to the wider population of patients with AF.

Prophylactic intravenous magnesium sulphate in addition to oral {beta}-blockade does not prevent atrial arrhythmias after coronary artery or valvular heart surgery: a randomized, controlled trial

BACKGROUND

Atrial arrhythmias (AA) are an important cause of morbidity after cardiac surgery. Efforts at prevention of postoperative AA have been suboptimal. Perioperative beta-blocker administration is the standard of care at many centers. Although prophylactic administration of magnesium sulfate (MgSO(4)) has been recommended, review of all previously published trials of MgSO(4) reveals conflicting results. This study was designed to address methodological shortcomings from previous studies and is the largest randomized, placebo-controlled trial of intravenous (IV) MgSO(4) for the prevention of AA after coronary artery bypass grafting or cardiac valvular surgery.

METHODS AND RESULTS

A total of 927 nonemergent cardiac surgery patients were stratified into 2 groups: isolated coronary artery bypass grafting (n=694), or valve surgery with or without coronary artery bypass grafting (n=233), and randomized to receive either 5g IV MgSO(4) or placebo on removal of the cross-clamp, followed by daily 4-hour infusions, from postoperative day 1 until postoperative day 4. All patients were treated according to an established oral beta-blocker protocol. Postoperative serum Mg levels were checked and standard of care was to administer IV MgSO(4) for low serum levels. The primary end point was AA lasting > or =30 minutes or requiring treatment for hemodynamic compromise. There were no differences in the incidence of AA between patients who received IV MgSO(4) or placebo (26.4% versus 24.3%, respectively). The results were similar when broken down according to stratified groups.

CONCLUSIONS

In patients treated with a protocol for postoperative oral beta-blocker after nonemergent cardiac surgery, the addition of prophylactic IV MgSO(4) did not reduce the incidence of AA.

Postoperative atrial fibrillation

Atrial fibrillation is a common arrhythmia that occurs after cardiac surgery. It is associated with an increase in morbidity, length of hospital stay and mortality. Patients who are at higher risk of postoperative atrial fibrillation should receive prophylactic treatment. Atrial fibrillation usually resolves spontaneously after heart rate is controlled; however, if patients are highly symptomatic or hemodynamically unstable, sinus rhythm should be restored by electrical or pharmacologic cardioversion.

Magnesium sulphate and amiodarone prophylaxis for prevention of postoperative arrhythmia in coronary by-pass operations

Background

The aim of this study was to investigate the use of prophylactic magnesium sulphate and amiodarone in treating arrhythmias that may occur following coronary bypass grafting operations.

Methods

The study population consisted of 192 consecutive patients who were undergoing coronary artery bypass grafting (CABG). Sixty-four patients were given 3 g of magnesium sulphate (MgSO4) [20 ml = 24.32 mEq/L Mg⁺²] in 100 cc of isotonic 0.9% solution over 2 hours intravenously at the following times: 12 hours prior to the operation, immediately following the operation, and on postoperative days 1, 2, and 3 (Group 1). Another group of 64 patients was given a preoperative infusion of amiodarone (1200 mg) on first post-operative day (Group 2). After the operation amiodarone was administered orally at a dose of 600 mg/day. Sixty-four patients in group 3 (control group) had 100 cc. isotonic 0.9% as placebo, during the same time periods.

Results

In the postoperative period, the magnesium values were significantly higher in Group 1 than in Group 2 for all measurements. The use of amiodarone for total arrhythmia was significantly more effective than prophylactic treatment with magnesium sulphate (p = 0.015). There was no difference between the two drugs in preventing supraventricular arrhythmia, although amiodarone significantly delayed the revealing time of atrial fibrillation (p = 0.026). Ventricular arrhythmia, in the form of ventricular extra systole, was more common in the magnesium prophylaxis group. The two groups showed no significant differences in other operative or postoperative measurements. No side effects of the drugs were observed.

Conclusion

Prophylactic use of magnesium sulphate and amiodarone are both effective at preventing arrhythmia that may occur following coronary by-pass operations. Magnesium sulphate should be used in prophylactic treatment since it may decrease arrhythmia at low doses. If arrhythmia should occur despite this treatment, intervention with amiodarone may be preferable.

Does Sodium Nitroprusside Decrease the Incidence of Atrial Fibrillation After Myocardial Revascularization?

Background— Atrial fibrillation (AF) often occurs after coronary artery bypass grafting and can result in increased morbidity and mortality. In the present pilot study, our aim was to investigate whether sodium nitroprusside (SNP), as a nitric oxide donor, can reduce the frequency of post–coronary artery bypass grafting AF.

Methods and Results— To investigate the effectiveness of SNP in the prophylaxis of AF, we conducted a prospective, randomized, placebo-controlled clinical study on 100 consecutive patients in whom we performed elective and initial CABG operations. A control group of 50 patients were treated with placebo (dextrose 5% in water), whereas the SNP group (n=50 patients) was treated with SNP (0.5 μg · kg −1 · min −1 ) during the rewarming period. High-sensitivity C-reactive protein levels were measured before surgery and 5 days postoperatively. All patients were monitored postoperatively with telemetry. Baseline characteristics were similar in both treatment groups. AF occurred in 12% of the SNP group and 27% of the control group. The occurrence of AF was significantly lower in the SNP group ( P =0.005). The duration of AF in the SNP group was significantly shorter than that in the control group (5.33±1.86 and 7.55±1.94 hours, respectively; P =0.023). C-reactive protein levels were higher postoperatively in the control group than in the SNP group ( P <0.05). Postoperative AF significantly prolonged postoperative hospital stay ( P <0.05).

Conclusions— The incidence of postoperative AF in the SNP group was reduced significantly. Further studies are needed to better delineate the anti-AF profile of SNP.

Clinical review: treatment of new-onset atrial fibrillation in medical intensive care patients--a clinical framework

Atrial fibrillation occurs frequently in medical intensive care unit patients. Most intensivists tend to treat this rhythm disorder because they believe it is detrimental. Whether atrial fibrillation contributes to morbidity and/or mortality and whether atrial fibrillation is an epiphenomenon of severe disease, however, are not clear. As a consequence, it is unknown whether treatment of the arrhythmia affects the outcome. Furthermore, if treatment is deemed necessary, it is not known what the best treatment is. We developed a treatment protocol by searching for the best evidence. Because studies in medical intensive care unit patients are scarce, the evidence comes mainly from extrapolation of data derived from other patient groups. We propose a treatment strategy with magnesium infusion followed by amiodarone in case of failure. Although this strategy seems to be effective in both rhythm control and rate control, the mortality remained high. A randomised controlled trial in medical intensive care unit patients with placebo treatment in the control arm is therefore still defendable.

Postoperative atrial fibrillation

Atrial fibrillation is a common arrhythmia after cardiac surgery. It is associated with an increase in morbidity, length of hospital stay, and mortality. Patients who are at higher risk of postoperative atrial fibrillation should receive prophylactic treatment. Atrial fibrillation usually resolves spontaneously after heart rate is controlled; however, if patients are highly symptomatic or hemodynamically unstable, sinus rhythm should be restored by electrical or pharmacologic cardioversion. Patients with atrial fibrillation of more than 48 hours should receive antithrombotic therapy for thromboembolism prevention.

Prevention of atrial fibrillation after cardiac surgery

Atrial fibrillation is the most common arrhythmia occurring after heart surgery. Its prevalence after coronary artery bypass surgery is 17-33%. Atrial fibrillation requires additional treatment, lengthens hospitalization and increases the overall expenses of cardiac surgery. Atrial fibrillation can cause hemodynamic problems, predispose to congestive heart failure and increase the risk of stroke. Beta-blockers have been shown to effectively prevent atrial fibrillation, and beta-blockers should be a part of the medication of every patient undergoing cardiac surgery, if there are no contraindications. Amiodarone therapy can also be considered for especially high-risk patients.

Effect of renin-angiotensin aldosteron system blockers on postoperative atrial fibrillation

BACKGROUND

No randomized studies have been conducted to evaluate the effects of renin-angiotensin aldosteron system blockers on postoperative atrial fibrillation (AF). The aim of this study was to evaluate the effect of angiotensin converting-enzyme inhibitors (ACEIs) and ACEI plus candesartan, an angiotensin receptor blocker on postoperative AF.

METHODS

A group of consecutive patients undergoing coronary artery bypass and/or valve surgery was studied (n=128). The patients were randomized to ACEI group (n=49) and ACEI plus candesartan group (n=49). Thirty patients not on ACEI or angiotensin receptor blocker constituted the control group.

RESULTS

The rate of postoperative AF was higher in the control group (33.3%) compared to the ACEI group (12.2%, p=0.02) or ACEI plus candesartan group (10.2%, p=0.01). With the Cox proportional model, univariable negative predictors of postoperative AF, were the use of ACEI (RR 0.34, 95% CI 0.12 to 0.93, p=0.03) and the use of ACEI plus candesartan (RR 0.28, 95% CI 0.09 to 0.83, p=0.02); the positive predictor of postoperative AF was age>or=65 (RR 3.10, 95% CI 1.30 to 7.37, p=0.01). With the multivariable Cox proportional model, the only predictor of postoperative AF was age>or=65 (RR 9.70, 95% CI 2.04 to 46.1, p=0.004).

CONCLUSION

ACEI alone and ACEI plus candesartan decrease the incidence of postoperative AF compared to the control group. Candesartan has no additional effect on the rates of postoperative AF when added to ACEI.

Amiodarone Prophylaxis for Atrial Fibrillation After Cardiac Surgery: Meta-Analysis of Dose Response and Timing of Initiation

STUDY OBJECTIVE

To investigate a possible dose-response relationship between amiodarone and reduction in incidence of postoperative atrial fibrillation, and to determine whether pre- or postoperative initiation of amiodarone is superior.

DESIGN

Meta-analysis of randomized controlled trials.

DATA SOURCE

MEDLINE and EMBASE databases and the Cochrane Central Register of Controlled Trials for English-language reports published between 1966 and December 2005.

MEASUREMENTS AND MAIN RESULTS

Of 23 identified randomized controlled trials of amiodarone prophylaxis of postoperative atrial fibrillation, 14 were included in the final analysis. These studies enrolled a total of 2864 patients. For each study, the total administered amiodarone dose--categorized as low (< 3000 mg), medium (3000-5000 mg), or high (> 5000 mg)--and preoperative versus postoperative initiation were aggregated by using meta-analytic techniques. The incidence of postoperative atrial fibrillation was significantly reduced by amiodarone compared with placebo (p<0.001). Although the odds of developing atrial fibrillation appeared to be somewhat higher in the low-dose group, no significant differences were noted in the odds ratios (ORs) of developing atrial fibrillation among the low-, medium-, and high-dose groups: OR 0.58, 95% confidence interval (CI) 0.44-0.77; OR 0.45, 95% CI 0.30-0.69; and OR 0.44, 95% CI 0.33-0.58; respectively (p=0.238). In addition, the ORs for atrial fibrillation development associated with preoperative and postoperative initiation of amiodarone were not significantly different (OR 0.50, 95% CI 0.39-0.63; and OR 0.48, 95% CI 0.37-0.63; respectively, p=0.862).

CONCLUSION

Total amiodarone doses of 3000 mg or higher may be more effective than lower doses in reducing the rate of postoperative atrial fibrillation after cardiac surgery. Preoperative initiation of amiodarone appears to be unnecessary. These findings require confirmation in prospective, randomized trials.

Prophylactic Amiodarone for Prevention of Atrial Fibrillation After Cardiac Surgery: A Meta-Analysis

Amiodarone has been proposed to decrease atrial fibrillation after cardiac surgery. The literature was systematically reviewed for randomized trials comparing amiodarone with control for prevention of atrial fibrillation. Data were extracted on study characteristics, quality, and incidence of atrial fibrillation, cardiovascular outcomes, and length of hospitalization. Nineteen trials were included. Amiodarone reduced the odds ratio of atrial fibrillation (0.50; 95% confidence interval [CI]: 0.43 to 0.59, p < 0.0001), ventricular tachyarrhythmias (0.39; 95% CI: 0.26 to 0.58, p < 0.0001), and strokes (0.53; 95% CI: 0.30 to 0.92, p = 0.02). Amiodarone reduced hospital stay (0.6 days; 95% CI: 0.4 to 0.8, p < 0.0001). Amiodarone decreased atrial fibrillation, reduced perioperative ventricular tachyarrhythmias and strokes, and reduced duration of hospitalization. The current evidence supports recommending the routine use of perioperative amiodarone for cardiac surgery.

Cost-effectiveness of amiodarone for prophylaxis of atrial fibrillation after cardiothoracic surgery

STUDY OBJECTIVE

To determine whether prophylactic amiodarone, dosed according to Atrial Fibrillation Suppression Trial (AFIST) I and II regimens, is a cost-effective strategy for prevention of postoperative atrial fibrillation.

DESIGN

Cost-effectiveness analysis of retrospective cohort study.

SETTING

Urban, academic hospital.

PATIENTS

A total of 2046 patients who underwent cardiothoracic surgery between February 1, 1998, and October 31, 2003. Of these patients, 186 received amiodarone and 1860 served as controls.

MEASUREMENTS AND MAIN RESULTS

Each patient who received prophylactic amiodarone using the AFIST I or II dosing strategies was matched for age, sex, history of valvular surgery, history of atrial fibrillation, beta-blocker intolerance, and receipt of preoperative digoxin therapy with 10 patients who did not receive prophylactic amiodarone. Occurrence of postoperative atrial fibrillation, total hospital costs, and both intensive care unit (ICU) and total hospital length of stay (LOS) were compared between groups. Nonparametric bootstrapping was conducted to examine study results as part of a quadrant analysis and to calculate confidence intervals for the incremental cost-effectiveness ratio. The ICU and total hospital LOS, and total costs for patients with and without postoperative atrial fibrillation were also compared. Fewer patients receiving prophylactic amiodarone developed postoperative atrial fibrillation compared with controls (23.1% vs 29.9%, p=0.05). Total hospital costs for the amiodarone group were 28% less than those for the control group (24,131 US dollars +/- 26,539 vs 33,518 US dollars +/- 40,892, p=0.002). Approximately 98% of the time, patients receiving amiodarone prophylaxis fell into the quadrant that showed superior efficacy and lower total costs. Patients who developed postoperative atrial fibrillation, compared with those who did not, regardless of amiodarone prophylaxis, had a longer mean +/- SD stay in the ICU (6.9 +/- 17.1 vs 3.7 +/- 7.9 days, p<0.001), a longer mean total hospital LOS (14.8 +/- 18.8 vs 10.2 +/- 10.4 days, p+/-0.001), and higher mean total hospital costs (41,574 US dollars +/- 54,721 vs 28,968 US dollars +/- 31,046, p<0.001).

CONCLUSION

Prophylactic amiodarone was shown to reduce the occurrence of postoperative atrial fibrillation as well as total hospital costs in patients undergoing cardiothoracic surgery. In patients who developed postoperative atrial fibrillation, both ICU and total hospital LOS as well as total hospital costs were increased.

Safety of amiodarone in the prevention of postoperative atrial fibrillation: A meta-analysis

PURPOSE

A meta-analysis was conducted to assess the safety of amiodarone in the prevention of postoperative atrial fibrillation.

METHODS

A search of the medical literature was conducted to identify randomized controlled trials of prophylactic amiodarone use in cardiothoracic surgery. Studies were independently reviewed by three investigators and selected for inclusion if they met the following three criteria: (1) randomized controlled trial of amiodarone versus placebo or routine treatment, (2) patients underwent coronary artery bypass graft or valvular surgery, and (3) reported data on the frequency of at least one of the following safety endpoints: bradycardia, hypotension, heart block, nausea, cerebral vascular accident, myocardial infarction, and death. Both random- and fixed-effects models were used to determine any significant associations between amiodarone and safety endpoints.

RESULTS

Eighteen trials were analyzed. A total of 3408 patients were enrolled in these trials (1736 received amiodarone and 1672 received placebo). Amiodarone increased the odds of developing bradycardia (odds ratio [OR], 1.70; 95% confidence interval [CI], 1.05-2.74) and hypotension (OR, 1.62; 95% CI, 1.04-2.54). The administration of i.v. amiodarone, an average daily dose exceeding 1 g, and postoperative amiodarone administration were each associated with a greater likelihood of hemodynamic adverse effects. Amiodarone did not appear to affect other safety endpoints.

CONCLUSION

Meta-analysis showed amiodarone to be associated with an increased risk of developing bradycardia and hypotension when used for the prophylaxis of postoperative atrial fibrillation. The greatest risk in the occurrence of these adverse events arose when using regimens containing i.v. amiodarone, initiating prophylaxis during the postoperative period, and using regimens with average daily doses exceeding 1 g.

Impact of Intravenous Magnesium on Post-Cardiothoracic Surgery Atrial Fibrillation and Length of Hospital Stay: A Meta-Analysis

Postoperative atrial fibrillation can occur in 25% to 40% of patients undergoing cardiothoracic surgery. Although the majority of postoperative atrial fibrillation is benign, it has been associated with prolonged hospital length of stay. Magnesium prophylaxis against postoperative atrial fibrillation has been evaluated in several clinical trials; however these trials were small in size and therefore conveyed mixed or inconclusive results. In an attempt to better understand magnesium's role in this setting, we conducted a meta-analysis. A systematic literature search was conducted from January 1999 through August 2004 to identify trials of prophylactic magnesium in the setting of cardiothoracic surgery. The primary outcome measure was the incidence of postoperative atrial fibrillation. Trials were further analyzed based on cumulative doses of magnesium and perioperative time of initiation of prophylaxis, as well as length of stay. Seven randomized trials were identified. Upon meta-analysis, magnesium was found to prevent postoperative atrial fibrillation with an odds ratio of 0.66 and 95% confidence interval of 0.51 to 0.87. The incidence of postoperative atrial fibrillation was also significantly reduced in the low dose with an odds ratio of 0.36 and 95% confidence interval of 0.23 to 0.56, and in the preoperative groups with an odds ratio of 0.46 and 95% confidence interval of 0.31 to 0.67. Prophylactic magnesium reduced length of stay (n = 6 studies) by a weighted mean difference of 0.29 days, with a 95% confidence interval 0.54 to 0.05. Prophylactic magnesium reduced cardiothoracic surgery patients' risk of postoperative atrial fibrillation and length of stay. Administering lower doses and initiating prophylaxis in the preoperative period achieved the greatest reduction in postoperative atrial fibrillation.

Effect of Prophylactic Amiodarone on Clinical and Economic Outcomes After Cardiothoracic Surgery: A Meta-Analysis

BACKGROUND:

Two previous meta-analyses of amiodarone for prevention of postoperative atrial fibrillation (POAF) after cardiothoracic surgery did not evaluate total hospital cost, concluded that data on stroke are incomplete, and did not evaluate the effect of clinical heterogeneity between trials.

OBJECTIVE:

To conduct a meta-analysis examining amiodarone's prophylactic impact on cardiothoracic surgery POAF, length of stay (LOS), stroke, and total costs.

METHODS:

Three reviewers conducted a systematic literature search of MEDLINE, EMBASE, CINAHL, and the Cochrane Library (1966–September 2004%). Studies were included if they met the following criteria: (1%) randomized controlled trial versus placebo/routine treatment, (2%) coronary artery bypass graft and/or valvular surgery, (3%) Jadad score ≥3, (4%) reported data on incidence of POAF or stroke, LOS, or total costs, (5%) used electrocardiographic/Holter monitoring, and (6%) monitored subjects for ≥2 days. A random-effects model was utilized. Subgroup and sensitivity analyses were conducted.

RESULTS:

Fifteen trials were identified, including 1512 and 1429 patients in the amiodarone and control groups, respectively. Amiodarone reduced POAF (OR 0.50; 95% CI 0.42 to 0.60%) and decreased stroke (n = 8 studies), LOS (n = 10%), and total costs (n = 6%) (OR 0.47; 95% CI 0.23 to 0.96; −0.73 days, 95% CI −0.95 to −0.51; and –$1619, 95% CI −3395 to 156, respectively). Surgery type, β-blocker use, route of administration, use of a fixed-effects model, or exclusion of unblinded/unpublished studies did not affect the overall results. No statistical heterogeneity was observed for any endpoint evaluated (p > 0.22 for all comparisons).

CONCLUSIONS:

Prophylactic treatment with amiodarone decreases patients' risk of POAF and stroke while reducing LOS.

Three-day magnesium administration prevents atrial fibrillation after coronary artery bypass grafting

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.

Intravenous magnesium for prevention of atrial fibrillation after coronary artery bypass surgery: a systematic review and meta-analysis

Atrial fibrillation (AF) is one of the most common complications after coronary artery bypass surgery. The objective of this study was to assess the effectiveness of intravenous magnesium in preventing postoperative atrial fibrillation. A meta-analysis of eight identified randomized controlled trials, reporting comparisons between magnesium and control was undertaken. The primary outcome was incidence of postoperative atrial fibrillation. Our review revealed that use of intravenous magnesium is associated with a significant reduction in the incidence of atrial fibrillation after coronary artery bypass surgery, with a relative risk of 0.64 (95% confidence interval = 0.47, 0.87, and p = 0.004).

Pharmacologic Prophylaxis

New-onset atrial fibrillation (AF) occurs frequently in patients after cardiac surgery. The purpose of this study was to review the published trials and to provide clinical practice guidelines for pharmacologic prophylaxis against postoperative AF. Trials of pharmacologic prophylaxis against AF after heart surgery were identified by searching MEDLINE, the Cochrane Controlled Trials Register, and the bibliographies of published reports. Evidence grades and clinical recommendation scores were assigned to each prophylactic drug based on published evidence. Ninety-one trials were identified. The primary study design was a randomized, controlled trial of one drug vs placebo/usual care. Pharmacologic therapies that are reviewed include Vaughan-Williams class II agents (ie, beta-receptor antagonists) [29 trials; 2,901 patients], Vaughan-Williams class III agents (ie, sotalol and amiodarone) [18 trials; 2,978 patients], Vaughan-Williams class IV agents (ie, verapamil and diltiazem) [5 trials; 601 patients], and Vaughan-Williams class I agents (ie, quinidine and procainamide) [3 trials; 246 patients], as well as digitalis (10 trials; 1,401 patients), magnesium (14 trials; 1,853 patients), dexamethasone (1 trial; 216 patients), glucose-insulin-potassium (3 trials; 102 patients), insulin (1 trial; 501 patients), triiodothyronine (2 trials; 301 patients), and aniline (1 trial; 32 patients). A consistent finding in this review is that antiarrhythmic drugs with beta-adrenergic receptor-blocking effects (ie, class II beta-blockers, sotalol, and amiodarone) demonstrated successful prophylaxis. Furthermore, those therapies that did not inhibit beta-receptors generally failed to demonstrate a decreased incidence in postoperative AF. While sotalol and amiodarone have been shown in some studies to be effective, their safety and the incremental prophylactic advantage in comparison with beta-blockers has not been conclusively demonstrated. On the basis of evidence that has been reviewed and graded for quality, it is recommended that strong consideration should be given to the prophylactic administration of Vaughan-Williams class II beta-blocking drugs as a means of lowering the incidence of new-onset post-cardiac surgery AF.

Effects of magnesium on atrial fibrillation after cardiac surgery: a meta-analysis

OBJECTIVES

To assess the efficacy of the administration of magnesium as a method for the prevention of postoperative atrial fibrillation (AF) and to evaluate its influence on hospital length of stay (LOS) and mortality.

METHODS

Literature search and meta-analysis of the randomised control studies published since 1966.

RESULTS

20 randomised trials were identified, enrolling a total of 2490 patients. Study sample size varied between 20 and 400 patients. Magnesium administration decreased the proportion of patients developing postoperative AF from 28% in the control group to 18% in the treatment group (odds ratio 0.54, 95% confidence interval (CI) 0.38 to 0.75). Data on LOS were available from seven trials (1227 patients). Magnesium did not significantly affect LOS (weighted mean difference -0.07 days of stay, 95% CI -0.66 to 0.53). The overall mortality was low (0.7%) and was not affected by magnesium administration (odds ratio 1.22, 95% CI 0.39 to 3.77).

CONCLUSION

Magnesium administration is an effective prophylactic measure for the prevention of postoperative AF. It does not significantly alter LOS or in-hospital mortality.

Pharmacologic prophylaxis for postoperative atrial tachyarrhythmia in general thoracic surgery: Evidence from randomized clinical trials

BACKGROUND

Atrial tachyarrhythmia is the most common complication after general thoracic surgery and is associated with significant morbidity, longer hospital stay, and higher costs. We sought to determine whether the use of antiarrhythmic medications is associated with a reduced rate of postoperative atrial tachyarrhythmia.

METHODS

MEDLINE, EMBASE, Cochrane Database of clinical trials (1980-2003), and reference lists of relevant articles were searched for randomized controlled trials with placebo control, general thoracic patients, and noncombined and prophylactic use of the medications. Search, data abstraction, and analyses were performed and confirmed by at least 2 authors. A fixed-effects model was used to perform meta-analyses.

RESULTS

There were 11 unique trials (total n = 1294) that met the inclusion criteria. Calcium-channel blockers and beta-blockers reduced the risk of atrial tachyarrhythmia in 4 and 2 trials, respectively (relative risk of 0.50 and 95% confidence interval of 0.34-0.73; relative risk of 0.40 and 95% confidence interval of 0.17-0.95, respectively). However, beta-blockers tended to increase the risk of pulmonary edema (relative risk, 2.15; 95% confidence interval, 0.74-6.23). Magnesium tested in one unblinded trial also reduced the risk of atrial tachyarrhythmia (relative risk, 0.4; 95% confidence interval, 0.21-0.78). On the other hand, digitalis preparations were found to be harmful because they increased the risk of atrial tachyarrhythmia in 3 trials (relative risk, 1.51; 95% confidence interval, 1.00-2.28). Finally, 2 other medications, flecainide and amiodarone, were each tested in a single small trial, and their effects were associated with great uncertainty.

CONCLUSIONS

Calcium-channel blockers and beta-blockers are effective in reducing postoperative atrial tachyarrhythmia. The use of these medications should be individualized, and possible adverse events of beta-blockers should be taken into account. Randomized clinical trials do not support the use of digitalis in general thoracic surgery. The value of magnesium as a supplement to a main prophylactic regimen should be explored.

Atrial fibrillation after cardiac surgery: an evidence-based approach to prevention

A number of advances in surgical and anesthetic techniques have reduced the risk for patients undergoing cardiac surgery. However, postoperative atrial fibrillation remains common, with an incidence ranging between 25% and 40%. It is associated with an increased incidence of congestive heart failure, renal insufficiency, and stroke that prolongs hospitalization and increases rates of readmission after discharge. Consequently, there has been great interest in strategies to prevent this arrhythmia. When both safety and efficacy are considered, the available evidence to date suggests that only beta-blockers can be recommended for the prevention of atrial fibrillation after cardiac surgery. Other treatments might be considered on an individual basis after careful consideration of the patient's potential for side effects.