Giving IV and Oral Amiodarone Perioperatively for the Prevention of Postoperative Atrial Fibrillation in Patients Undergoing Coronary Artery Bypass Surgery

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.

Prevention of postoperative atrial fibrillation in cardiac surgery: a quality improvement project

PURPOSE

Postoperative atrial fibrillation (POAF) has an incidence of 20-60% in cardiac surgery. The Society of Cardiovascular Anesthesiologists and the European Association of Cardiothoracic Anaesthesiology Practice Advisory have recommended postoperative beta blockers and amiodarone for the prevention of POAF. By employing quality improvement (QI) strategies, we sought to increase the use of these agents and to reduce the incidence of POAF among our patients undergoing cardiac surgery.

METHODS

This single-centre QI initiative followed the traditional Plan, Do, Study, Act (PDSA) cycle scientific methodology. A POAF risk score was developed to categorize all patients undergoing cardiac surgery as either normal or elevated risk. Risk stratification was incorporated into a preprinted prescribing guide, which recommended postoperative beta blockade for all patients and a postoperative amiodarone protocol for patients with elevated risk starting on postoperative day one (POD1). A longitudinal audit of all patients undergoing cardiac surgery was conducted over 11 months to track the use of prophylactic medications and the incidence of POAF.

RESULTS

Five hundred and sixty patients undergoing surgery were included in the QI initiative from 1 December 2020 to 1 November 2021. The baseline rate of POAF across all surgical subtypes was 39% (198/560). The use of prophylactic amiodarone in high-risk patients increased from 13% (1/8) at the start of the project to 41% (48/116) at the end of the audit period. The percentage of patients receiving a beta blocker on POD1 did fluctuate, but remained essentially unchanged throughout the audit (34.8% in December 2020 vs 46.7% in October 2021). After 11 months, the overall incidence of POAF was 29% (24.9% relative reduction). Notable reductions in the incidence of POAF were observed in more complex surgical subtypes by the end of the audit, including multiple valve replacement (89% vs 56%), aortic repair (50% vs 33%), and mitral valve surgery (45% vs 33%).

CONCLUSIONS

This single-centre QI intervention increased the use of prophylactic amiodarone by 28% for patients at elevated risk of POAF, with no change in the early postoperative initiation of beta blockers (46.7% of patients by POD1). There was a notable reduction in the incidence of POAF in patients at elevated risk undergoing surgery.

Healthcare resource utilization and costs for patients with postoperative atrial fibrillation in the United States

BACKGROUND

Postoperative atrial fibrillation (POAF) is one of the most common complications following cardiac surgery. POAF is associated with increased hospitalization costs, but its long-term economic burden is not well defined.

OBJECTIVE

To assess 30-day and 1-year incremental healthcare resource utilization (HRU) and costs associated with POAF in the United States (US).

METHODS

This retrospective cohort study used claims data from the IBM Watson MarketScan database. A cohort of US adults aged 55--90 years who underwent open-heart surgery between 1 January 2017 and 31 December 2018 was used to compare patients who experienced POAF versus patients who did not (controls). The outcomes of interest were incremental HRU and costs, which were assessed during the index hospitalization and 30-day and 1-year postdischarge time periods. Inverse probability weighting was used to adjust for differences in baseline characteristics.

RESULTS

A total of 8,020 patients met the study inclusion criteria with 5,765 patients in the control cohort (mean age, 63.4 years) and 2,255 patients in the POAF cohort (mean age, 65.8 years). After adjustment, patients with POAF had an index hospitalization that was 1.9 days longer (99% CI, 1.3-2.4 days; p < 0.001) and cost $13,919 more (99% CI, $2,828-$25,011; p < 0.001) than for patients without POAF. POAF patients also had significantly higher HRU at 30 days and 1-year postdischarge with incremental costs of $4,649 (99% CI, $1,479-$7,819; p < 0.001) and $10,671 (99% CI, $2,407-$18,935; p < 0.001), respectively.

CONCLUSION

POAF following open-heart surgery poses a significant economic burden up to 1 year postdischarge.

Use of an antiarrhythmic drug against acute selenium toxicity

OBJECTIVE

Selenium is an essential trace element. But, selenium may have toxic effects in high doses. There are no proven antidotes or curative treatments for acut selenium toxicity. Treatment involves stopping the exposure and providing supportive care for symptoms. Therefore, it is necessary to find more effective substances in the treatment of selenium toxicity. The aim of this study was to increase the survival rate of animals by supporting the heart with amiodarone and to determine the effect of amiodarone on the pathological, hematological and biochemical parameters in acute selenium intoxication.

METHODS

64 Wistar-Albino rats were divided into four groups. Group I was given only distilled water, Group II was given 18 mg/kg dose of amiodarone, Group III was given 18 mg/kg amiodarone and 10 mg/kg sodium selenite and Group IV was given sodium selenite 10 mg/kg (LD₅₀ dose)orally.

RESULTS

11 of the 16 animals in Group IV died within the first 48 h of drug administration. However, no deaths were observed in the rats in Group III. No hematological changes were observed. Biochemically, CK, CK-MB and LDH levels of Group IV were higher than the other groups on both the 2nd and 10th days. In Groups II and III, this serum level decreased, and vitamin B12 levels increased. In macroscopic inspections of the organs of Groups III and IV, slight paleness was detected. Histopathologically, degenerative changes in tissue were observed, especially in Group IV.

CONCLUSION

This study shows that amiodarone application has a reducing effect on selenium toxicity. This was because amiodarone protected the heart by reducing CK and CK-MB levels and increased vitamin B12 levels, which play a role in the synthesis of S-adenosyl methionine that converts selenium into a nontoxic form.

Dexmedetomidine sedation reduces atrial fibrillation after cardiac surgery compared to propofol: a randomized controlled trial

BACKGROUND

Atrial fibrillation occurs frequently in patients following cardiac surgery and can be a cause of increased morbidity and mortality. The use of dexmedetomidine to prevent atrial fibrillation is unclear. The present study was designed to evaluate the effect of dexmedetomidine sedation on the incidence of atrial fibrillation after cardiac surgery.

METHODS

Upon arrival to the intensive care unit (ICU), cardiac surgery patients without prior atrial fibrillation or flutter were randomized to receive either dexmedetomidine (0.2-1.5 μg/kg/h) or propofol (0.3-3 mg/kg/h) open-label titrated to a target Richmond agitation-sedation scale of 0 to -3. Our primary endpoint was the incidence of postoperative atrial fibrillation, and the secondary end points were the length of ICU stay, length of hospital stay, and hospital costs.

RESULTS

Atrial fibrillation occurred in 6 of 44 patients (13.6 %) in the dexmedetomidine group compared to 16 of 44 patients (36.4 %) in the propofol group (odds ratio = 0.28; 95 % confidence interval, 0.10, 0.80; P = 0.025). The median (interquartile range) length of ICU stay in the dexmedetomidine group was significantly lower than in the propofol group (2.9 (2.4-3.5) vs 3.5 (2.7-4.5 days, P = 0.008), with a trend toward a decrease in median hospital costs (86,367 vs 77,874 Chinese yuan; P = 0.068). The incidence of hypotension was higher in the dexmedetomidine group than in the propofol group (25/44 (56.8 %) vs 13/44 (29.5 %); P = 0.017).

CONCLUSIONS

Dexmedetomidine sedation reduced the incidence of new-onset postoperative atrial fibrillation and shortened the length of ICU stay in patients after cardiac surgery compared to propofol sedation. Dexmedetomidine treatment was associated with more episodes of hypotension.

TRIAL REGISTRATION

chictr.org.cn: ChiCTR-IPR-16008231 , retrospectively registered: April 6, 2016. This trial was not prospectively registered due to a lack of importance applied to trial registration.

Is the Preoperative Administration of Amiodarone or Metoprolol More Effective in Reducing Atrial Fibrillation: After Coronary Bypass Surgery?

This study examined the influence of preoperative administration of amiodarone and metoprolol in preventing postoperative atrial fibrillation (AF) after coronary artery bypass grafting (CABG) surgery.The study comprised 251 patients who underwent CABG surgery at our hospital between January 2012 and May 2014. The patients were randomly divided into 2 groups: amiodarone therapy group (n = 122 patients) and metoprolol therapy group (n = 129 patients).In the amiodarone group, the patients received amiodarone tablet orally 1 week before coronary bypass surgery and during the postoperative period. In the metoprolol group, the patients received metoprolol tablet orally 1 week before surgery and during the postoperative period. The AF development rate was retrospectively evaluated between the first 3 days and 4 weeks after surgery.AF developed in 14 patients in the amiodarone group and 16 patients in the metoprolol group 4 weeks after the operation (P = 0.612).No significant difference was observed between the groups in terms of intensive care unit and hospital stay. Furthermore, hospital charges were similar in both groups (P = 0.741).The results of the logistic regression analysis showed age, left ventricular ejection fraction, left atrial diameter, and aortic cross-clamping time to be predictors for postoperative AF.This study demonstrates that amiodarone and metoprolol have similar effects in prevention of AF after cardiac surgery. However, larger-scale studies need to be conducted to substantiate these findings.

The effect of lidocaine and amiodarone on prevention of ventricular fibrillation in patients undergoing coronary artery bypass grafting

OBJECTIVE

Ventricular fibrillation is common after aortic declamping in patients undergoing open heart surgery. This situation has a negative impact on morbidity and mortality. The aim of this prospective study was to compare the effect of administering lidocaine versus amiodarone before aortic declamping during elective coronary bypass grafting, paying close attention to when the initial effect of amiodarone sets in.

METHODS

In this double blind, prospective, randomized, controlled study, 86 patients who were candidates for elective coronary artery bypass grafting were recruited into three groups: group lidocaine (group L, n=29); group amiodarone (group A, n=27); and group placebo (group P, n=30). Group L patients received 1.5 mg/kg of lidocaine 2 minutes before aortic declamping and group A patients received 300 mg of amiodarone intravenously 15 minutes before release of the aortic cross clamp. The primary endpoints were the incidence of ventricular fibrillation and the number of shocks required to terminate ventricular fibrillation.

RESULTS

The frequency of ventricular fibrillation occurrence was significantly higher in group P (70%) when compared with group A (37%) and group L (38%) (P=.017). There was no statistically significant difference between the amiodarone and the lidocaine groups regarding ventricular fibrillation. However, when ventricular fibrillation occurred, the percentage of patients requiring electrical defibrillation was significantly higher in both group L and group P when compared with group A (P=.023).

CONCLUSION

We suggest that during coronary arterial bypass surgery, administration of an amiodarone regime before release of the aortic cross clamp, paying particular attention to the start of the initial effect of amiodarone, is no more effective than lidocaine for prevention from arrhythmia; however, amiodarone reduces the need for electrical defibrillation.

Predicting New-Onset Postoperative Atrial Fibrillation in Cardiac Surgery Patients

OBJECTIVE

To derive a simple clinical prediction rule identifying patients at high risk of developing new-onset postoperative atrial fibrillation (POAF) after cardiac surgery.

DESIGN

Retrospective analysis on prospectively collected observational data.

SETTING

A university-affiliated cardiac hospital.

PARTICIPANTS

Adult patients undergoing coronary artery bypass grafting and/or valve surgery.

INTERVENTIONS

Observation for the occurrence of new-onset postoperative atrial fibrillation.

MEASUREMENTS AND MAIN RESULTS

Details on 28 preoperative variables from 999 patients were collected and significant predictors (p<0.2) were inserted into multivariable logistic regression and reconfirmed with recursive partitioning. A total of 305 (30.5%) patients developed new-onset POAF. Eleven variables were associated significantly with atrial fibrillation. A multivariable logistic regression model included left atrial dilatation, mitral valve disease, and age. Coefficients from the model were converted into a simple 7-point predictive score. The risk of POAF per score is: 15.0%, if 0; 20%, if 1; 27%, if 2; 35%, if 3; 44%, if 4; 53%, if 5; 62%, if 6; and 70%, if 7. A score of 4 has a sensitivity of 44% and a specificity of 82% for POAF. A score of 6 has a sensitivity of 11% and a specificity of 97%. Bootstrapping with 5,000 samples confirmed the final model provided consistent predictions.

CONCLUSIONS

This study proposed a simple predictive score incorporating three risk variables to identify cardiac surgical patients at high risk of developing new-onset POAF. Preventive treatment should target patients ≥ 65 years with left atrial dilatation and mitral valve disease.

Association of perioperative troponin and atrial fibrillation after coronary artery bypass grafting

OBJECTIVES

Prediction of atrial fibrillation (AF) after coronary artery bypass grafting (CABG) may lead to preventive or early treatment and improved outcome. We investigated the association of serial perioperative cardiac troponin T (cTNT) measurements with postoperative AF in patients undergoing CABG.

METHODS

In a retrospective analysis of prospectively collected data, 3148 patients undergoing elective CABG were evaluated. cTNT values were routinely determined before the start of surgery (cTNT0), at arrival on the intensive care unit (cTNT1) and 8-12 h later (cTNT2). Measurement of cTNT was continued until the peak value was reached. The development of AF during hospital stay was scored. The association between cTNT (cTNT0, cTNT1, cTNT2 and cTNTmax in first 48 h) and AF was calculated in univariable and multivariable analysis.

RESULTS

AF occurred in 1080 (34%) patients. cTNT0, cTNT2 and cTNTmax were significantly and positively associated with postoperative AF (P < 0.001) in a univariable analysis, whereas a trend was seen for cTNT1 (P = 0.051). Advanced age, inotropic support and postoperative infection were independently associated with postoperative AF after logistic regression analysis, but cTNT was not. Categorizing patients by inotropic support into categories of inotropic support duration (none, <48 h, >48 h), the mean cTNT values were significantly higher among patients with AF in each category (all P < 0.001). Perioperative cTNT was significantly higher in patients with postoperative complications, longer hospital stay and reduced in-hospital survival.

CONCLUSIONS

Perioperative cTNT is univariably associated with postoperative AF after CABG, but not independently. Further, no clinically useful cut-off point for preventive or early treatment could be identified. Both perioperative cTNT and postoperative AF are associated with negative outcome and prolonged hospital stay.

Epidural analgesia for cardiac surgery

BACKGROUND

A combination of general anaesthesia (GA) with thoracic epidural analgesia (TEA) may have a beneficial effect on clinical outcomes by reducing the risk of perioperative complications after cardiac surgery.

OBJECTIVES

The objective of this review was to determine the impact of perioperative epidural analgesia in cardiac surgery on perioperative mortality and cardiac, pulmonary or neurological morbidity. We performed a meta-analysis to compare the risk of adverse events and mortality in patients undergoing cardiac surgery under general anaesthesia with and without epidural analgesia.

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials (CENTRAL) (2012, Issue 12) in The Cochrane Library; MEDLINE (PubMed) (1966 to November 2012); EMBASE (1989 to November 2012); CINHAL (1982 to November 2012) and the Science Citation Index (1988 to November 2012).

SELECTION CRITERIA

We included randomized controlled trials comparing outcomes in adult patients undergoing cardiac surgery with either GA alone or GA in combination with TEA.

DATA COLLECTION AND ANALYSIS

All publications found during the search were manually and independently reviewed by the two authors. We identified 5035 titles, of which 4990 studies did not satisfy the selection criteria or were duplicate publications, that were retrieved from the five different databases. We performed a full review on 45 studies, of which 31 publications met all inclusion criteria. These 31 publications reported on a total of 3047 patients, 1578 patients with GA and 1469 patients with GA plus TEA.

MAIN RESULTS

Through our search (November 2012) we have identified 5035 titles, of which 31 publications met our inclusion criteria and reported on a total of 3047 patients. Compared with GA alone, the pooled risk ratio (RR) for patients receiving GA with TEA showed an odds ratio (OR) of 0.84 (95% CI 0.33 to 2.13, 31 studies) for mortality; 0.76 (95% CI 0.49 to 1.19, 17 studies) for myocardial infarction; and 0.50 (95% CI 0.21 to 1.18, 10 studies) for stroke. The relative risks (RR) for respiratory complications and supraventricular arrhythmias were 0.68 (95% CI 0.54 to 0.86, 14 studies) and 0.65 (95% CI 0.50 to 0.86, 15 studies) respectively.

AUTHORS' CONCLUSIONS

This meta-analysis of studies, identified to 2010, showed that the use of TEA in patients undergoing coronary artery bypass graft surgery may reduce the risk of postoperative supraventricular arrhythmias and respiratory complications. There were no effects of TEA with GA on the risk of mortality, myocardial infarction or neurological complications compared with GA alone.

Management of arrhythmias in the perioperative setting

Perioperative arrhythmias are a common complication of surgery, with incidence ranging from 4% to 20% for noncardiothoracic procedures, depending on the type of surgery performed. The immediate postoperative period is a dynamic time and is associated with many conditions conducive to the development of postoperative arrhythmias. The presence of postoperative atrial fibrillation is associated with increased morbidity, ICU stay, length of hospitalization, and hospital costs. The associated burdens are expected to rise in the future, given that the population undergoing cardiac surgery is getting older and sicker. Thousands of patients undergo major surgery each year and a major complication of these procedures is the occurrence of perioperative arrhythmia. It is imperative for clinicians to be up-to-date on current management of these arrhythmias.

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.

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.

Intravenous and oral amiodarone for the prevention of postoperative atrial fibrillation in patients undergoing off-pump coronary artery bypass surgery

BACKGROUND

Atrial fibrillation is still a frequent complication that increases morbidity after coronary artery bypass grafting. This prospective randomized study is designed to define efficacy of postoperative amiodarone prophylaxis in preventing atrial fibrillation after off-pump coronary artery bypass grafting.

METHODS

One hundred forty-four patients who underwent elective off-pump coronary artery bypass grafting were enrolled for the study. Seventy-six patients (amiodarone group) received 5 mg/kg loading amiodarone infusion in the first postoperative hour, followed by 10 mg/kg for the first 24 hours. After 24 hours, patients received 600 mg/day amiodarone orally for 7 days and 200 mg/day until the end of the postoperative first month. Sixty-eight patients received placebo (control group).

RESULTS

Preoperative characteristics and operative variables of the patients were similar in both groups. Incidence of new-onset atrial fibrillation and maximal ventricular rate response were recorded. The incidence of new-onset atrial fibrillation (11.8% versus 26.5%) (P = .025) and maximal ventricular rate response (109 +/- 13.8 beats/min versus 124.5 +/- 13.9 beats/min) (P = .011) were significantly lower in the amiodarone group. Duration of atrial fibrillation was 17.5 +/- 8.1 hours for the amiodarone group compared with 32.7 +/- 12 hours for the control group (P = .002).

CONCLUSION

Postoperative intravenous amiodarone prophylaxis followed by oral amiodarone significantly reduces the incidence of atrial fibrillation after off-pump coronary artery bypass grafting and the ventricular rate during atrial fibrillation.

A practical guide for clinicians who treat patients with amiodarone: 2007

Amiodarone is commonly used to treat supraventricular and ventricular arrhythmias in various inpatient and outpatient settings. Over- and under-use of amiodarone is common, and data regarding patterns of use are sparse and largely anecdotal. Because of adverse drug reactions, proper use is essential to deriving optimal benefits from the drug with the least risk. This guide updates an earlier version published in 2000, reviews indications for use of amiodarone and recommends strategies to minimize adverse effects. The recommendations included herein are based on the best available data and the collective experience of the member of the writing committee.

Brain natriuretic peptide concentration in pericardial fluid is independently associated with atrial fibrillation after off-pump coronary artery bypass surgery

OBJECTIVES

Postoperative atrial fibrillation is associated with the increased incidence of morbidities and mortality. Predisposing determinants of atrial fibrillation development after off-pump coronary artery bypass grafting remain unclear. We hypothesized that pericardial fluid natriuretic peptide concentrations have a predictive value for developing postoperative atrial fibrillation in patients who have undergone off-pump coronary artery bypass grafting.

METHODS

We prospectively measured atrial natriuretic peptide and brain natriuretic peptide concentrations in plasma and pericardial fluid in 42 consecutive patients undergoing off-pump coronary artery bypass grafting, then continuously observed the occurrence of atrial fibrillation following off-pump coronary artery bypass grafting until the time of discharge.

RESULTS

Postoperative atrial fibrillation was documented in nine patients (21%, atrial fibrillation group), and not in 33 patients (no atrial fibrillation group). Between the groups, there was neither significant difference in plasma atrial natriuretic peptide concentrations nor in pericardial atrial natriuretic peptide concentrations. Plasma brain natriuretic peptide concentrations were comparable in both groups [56.2 (interquartile range 42.7-102.8) vs. 35.2 pg/ml (13.8-75.0), P=0.07]. Pericardial fluid brain natriuretic peptide concentrations were significantly higher in the atrial fibrillation group than in the no atrial fibrillation group [188.0 (124.8-411.0) vs. 39.3 pg/ml (10.0-88.4), P=0.0001]. In a multivariable logistic regression model, pericardial brain natriuretic peptide concentration was significantly associated with a higher risk of postoperative atrial fibrillation (odds ratio=3.0 every 50 pg/ml increase; 95% confidence interval, 1.1-8.6; P=0.04).

CONCLUSION

Our results suggested that pericardial fluid brain natriuretic peptide concentration is independently associated with the development of atrial fibrillation after off-pump coronary artery bypass grafting.

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.

Population modelling to describe pharmacokinetics of amiodarone in rats: Relevance of plasma protein and tissue depot binding

The objective of this paper was to characterize the disposition phase of AM in rats, after different high doses and modalities of i.v. administration. Three fitting programs, WINNONLIN, ADAPT II and NONMEM were employed. The two-stage fitting methods led to different results, none of which can adequately explain amiodarone's behaviour, although a great amount of data per subject is available. The non-linear mixed effect modelling approach allows satisfactory estimation of population pharmacokinetic parameters, and their respective variability. The best model to define the AM pharmacokinetic profile is a two-compartment model, with saturable and dynamic plasma protein binding and linear tissular depot dynamic binding. These results indicate that peripheral tissues act as depots, causing an important fall in AM plasma levels in the first moment after dosing. Later, the return of the drug from these depots causes a slow increase in serum concentration whenever the dose is reduced.

Risk-Stratified Evaluation of Amiodarone to Prevent Atrial Fibrillation After Cardiac Surgery

BACKGROUND

Amiodarone prophylaxis (AMP) reduces the prevalence of postoperative atrial fibrillation (POAF) after cardiac surgery. We investigated the impact of AMP on the frequency and duration of POAF, the intensive care unit and hospital length of stay, and its cost-effectiveness in a risk-stratified cohort.

METHODS

A retrospective, observational analysis of 509 patients who underwent cardiac surgery in 2003 was performed. Data sources included The Society of Thoracic Surgeons national database; medical and medication administration records; and the activity-based cost data from our institution. Risk stratification for POAF was determined using a validated risk index. Cost-effectiveness was determined from the hospital's perspective.

RESULTS

The mean patient age was 63 years, 27% were female, 80% underwent coronary artery bypass grafting, and 29% underwent valve surgery. When a risk-stratified evaluation was made, 50% of patients were at an elevated risk for having POAF develop. When compared with nonprophylaxed patients, those receiving AMP (59%) experienced less POAF (31% vs 22%; p = 0.027) and shorter durations of POAF (4.7 vs 2.7 days; p = 0.025). In the elevated-risk group, AMP clinically (but not significantly) reduced length of stay in the intensive care unit (101 vs 68 hours; p > 0.05) and post-procedural hospital length of stay (9.7 vs. 7.9 days, p > 0.05). In the elevated-risk group, AMP was robustly cost-effective in reducing POAF.

CONCLUSIONS

Amiodarone prophylaxis reduced the prevalence and duration of POAF. Baseline risk for POAF was a major determinant of the overall cost-effectiveness of AMP. The greatest cost savings with AMP was seen in patients at an elevated risk for POAF. These findings suggest the need for risk stratification when prescribing AMP.

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.

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.

Pharmacokinetics of Amiodarone in hyperlipidemic and simulated high fat-meal rat models

The objective of this study was to examine the effect of a high fat meal and hyperlipidemia on the pharmacokinetic behavior of amiodarone. To evaluate these effects, single doses of amiodarone were administered to rats i.v. (25 mg/kg) or orally (50 mg/kg). Some rats were rendered hyperlipidemic by intraperitoneal doses of poloxamer 407 followed by amiodarone i.v. In other normolipidemic rats, amiodarone was administered i.v. in a fasted state or after the administration of 1% cholesterol in peanut oil. Amiodarone plasma concentrations were considerably (>11-fold) increased in hyperlipidemia. Substantial decreases were noted in the clearance, volume of distribution and unbound fraction (11.6, 23 and 24.7-fold, respectively) in plasma of hyperlipidemic rats. Oral lipid caused a significant increase in plasma AUC(0-infinity) (1.38-fold) and a significant decrease in clearance (1.5-fold) of amiodarone after intravenous doses. Oral consumption of 1% cholesterol in peanut oil significantly increased the plasma AUC (1.83-fold) and bioavailability of amiodarone (1.31-fold) after oral doses. In determining oral bioavailability of lipophilic drugs such as amiodarone in food effect studies, in addition to the increase in absorption of drugs, other factors such as a decrease in clearance due to increases in lipoprotein levels should be taken into account.