Dronedarone for maintenance of sinus rhythm in atrial fibrillation or flutter

Latest drug developments in the field of cardiovascular disease

Cardiovascular disease has been responsible for more deaths annually than any other disease category since 1900, except for the influenza epidemic in 1916. Yet, the drug pipeline has been largely bereft of new entrants. In 2008, one new cardiovascular medication was marketed in the United States. In 2009, there were two new cardiovascular medications. In comparison, there were seven new drugs for oncology in 2009. The present review explores new agents within the context of models currently in the drug pipeline. Of course, there is no guarantee that any of these agents will be marketed. A discussion of the models is illustrative of the types of approaches being used to develop new cardiovascular agents.

Meta-analysis of cardiovascular outcomes with dronedarone in patients with atrial fibrillation or heart failure

Dronedarone is a benzofuran derivative approved by the Food and Drug Administration to decrease the risk of cardiovascular hospitalization in patients with paroxysmal or persistent atrial fibrillation (AF) and associated cardiovascular risk factors who are in sinus rhythm or will undergo cardioversion. There has been recent evidence to suggest that dronedarone may not have a favorable safety profile. We decided to evaluate all available evidence on the cardiovascular safety of this drug. A systematic search was made of the PubMed, CENTRAL, and EMBASE databases for randomized controlled trials from 1966 through 2011 comparing dronedarone to comparators in AF/heart failure. Intervention was dronedarone for AF for some studies and heart failure for others. Comparators included standard medical therapy and/or placebo and amiodarone for 1 study. Outcomes assessed were all-cause mortality, cardiovascular mortality, ventricular arrhythmias, embolic events, acute coronary syndrome, heart failure exacerbations, and hospitalization rates in the intervention versus comparator group at the end of ≥ 3 months of follow up with abstraction of data by 1 author. Seven randomized controlled trials were included in our analysis. Dronedarone use was associated with a trend toward worse all-cause and cardiovascular mortalities and increased heart failure exacerbations. It also showed numerically higher event rates for all other outcome events except acute coronary syndrome. Our pooled analysis showed increased all-cause and cardiovascular mortalities and increased heart failure exacerbations with use of dronedarone across a wide spectrum of populations. In conclusion, we recommend exercising caution using dronedarone, especially in patients with cardiovascular risk factors.

Antiarrhythmic drugs for the maintenance of sinus rhythm: risks and benefits

Atrial fibrillation (AF) is the most common arrhythmia seen in clinical practice, and its complications impose a significant economic burden. The development of more effective agents to manage patients with AF is essential. While clinical trials show no major differences in outcomes between rate and rhythm control strategies, some patients with AF require treatment with antiarrhythmic drugs (AADs) to maintain sinus rhythm, reduce symptoms, improve exercise tolerance, and improve quality of life. Currently available AADs, while effective, have limitations including limited efficacy, adverse events, toxicity, and proarrhythmic potential. The 6 most commonly used AADs (amiodarone, disopyramide, dofetilide [USA but not Europe], flecainide, propafenone, sotalol) have proarrhythmic effects (fewer with amiodarone). Amiodarone is the most effective AAD, but its safety profile limits its usefulness. Recent advances in AAD therapy include dronedarone and vernakalant. Dronedarone, approved by the United States Food and Drug Administration and the European Medicines Authority and others, has been proven efficacious in maintaining sinus rhythm and reducing the incidence of hospitalization due to cardiovascular events or death in patients with AF. The intravenous formulation of vernakalant is approved in the European Union, Iceland, and Norway. Oral vernakalant is currently undergoing evaluation for preventing AF recurrence and appears to be effective with an acceptable safety profile. Treatment should be individualized to the patient with consideration of pharmacologic risks and benefits according to AF management guidelines. Accumulating efficacy and safety data for new and emerging AADs holds promise for improved AF management and outcomes.

Stable cystatin C serum levels confirm normal renal function in patients with dronedarone-associated increase in serum creatinine

Dronedarone is a new antiarrhythmic drug for patients with nonpermanent atrial fibrillation (AF). A relatively consistent finding in all trials studying dronedarone was a moderate but significant elevation of serum creatinine. Since dronedarone competes for the same organic cation transporter in the distal renal tubule with creatinine, serum creatinine and its derived estimated glomerular filtration rate might not reflect true renal function in patients on dronedarone. We therefore investigated alternative markers for renal function in these patients. We prospectively included 20 patients with nonpermanent AF in whom dronedarone 400 mg twice daily was started. Patients had normal renal function and serum creatinine; serum cystatin C and creatinine clearance were measured before treatment and 10 and 90 days after treatment started. Mean serum creatinine level for all 20 patients at baseline (day 0) was 84.55 ± 12.14 and 87.8 ± 17.59 µmol/L on day 10. This slight increase in all patients was not significant. Patients were now divided into the predefined groups of "increased creatinine" (increase in serum creatinine level > 1 standard deviation) and "not increased creatinine." Patients with increased creatinine levels (n = 5) showed a significant elevation of serum creatinine levels from day 0 to day 10 (82.4 ± 9.18 to 104.4 ± 12.74 µmol/L; P = .003), whereas change in serum creatinine levels in the not increased creatinine group (n = 15) was not significant. Serum cystatin C levels remained stable in both of these groups (increased creatinine group: 0.76 ± 0.08 to 0.78 ± 0.08 mg/L; P = .65; not increased creatinine group: 0.77 ± 0.108 to 0.77 ± 0.107 mg/L; P = .906). In conclusion, cystatin C represents an easily available and reliable biomarker for estimation of true renal function in patients on dronedarone treatment.

Efficacy and safety profile of dronedarone in clinical practice. Results of the Magdeburg Dronedarone Registry (MADRE study)

BACKGROUND

Dronedarone is a new antiarrhythmic agent that has only recently been approved for the therapy of atrial fibrillation (AF). Results regarding a broader spectrum of patients and experience accumulated in clinical practice are still very scarce. Therefore, we prospectively investigated the efficacy and tolerance of dronedarone in a real life setting.

METHODS AND RESULTS

The study included 191 patients (85 women) aged 63 ± 9.9 years with a history of paroxysmal or persistent AF. Follow-up time was 14.3 ± 4.9 months. In patients with persistent AF, sinus rhythm was restored using electrical cardioversion prior to dronedarone administration. Each patient underwent standard ECG on a daily basis during the first 4 days of treatment, and on days 7, 30 and 90, resp. After that, the patients had a follow-up visit every three months. Creatinine, creatine kinase, and hepatic enzymes were closely monitored. Clinical history was meticulously taken at multiple follow-up visits. Dronedarone maintained sinus rhythm in 33.5% (95% CI: 27%-40%), and AF recurrence rate was high: 66.5% (95% CI: 60%-73%). Adverse effects occurred in 31.9% (95% CI: 27%-38%) of the patients and necessitated permanent discontinuation of dronedarone in 22% (95% CI: 17%-27%).

CONCLUSIONS

The results suggest that dronedarone may not be superior to available antiarrhythmic agents and caution against its use as a first line therapy in AF.

Atrial fibrillation in the elderly

This review discusses atrial fibrillation according to the guidelines of Brazilian Society of Cardiac Arrhythmias and the Brazilian Cardiogeriatrics Guidelines. We stress the thromboembolic burden of atrial fibrillation and discuss how to prevent it as well as the best way to conduct cases of atrial fibrillatios in the elderly, reverting the arrhythmia to sinus rhythm, or the option of heart rate control. The new methods to treat atrial fibrillation, such as radiofrequency ablation, new oral direct thrombin inhibitors and Xa factor inhibitors, as well as new antiarrhythmic drugs, are depicted.

Do the benefits of anti-arrhythmic drugs outweigh the associated risks? A tale of treatment goals in atrial fibrillation

Atrial fibrillation (AF) is the most common cardiac rhythm disorder and places a substantial burden on the US healthcare system. Unfortunately, there is no consensus as to whether patients should be treated with a primary rate- or rhythm-control strategy. The use of anti-arrhythmic drugs in the treatment of AF is discussed in the broader context of AF disease-management strategies with a focus on rhythm control. Outside of rhythm/ECG, AF treatment targets and cardiovascular outcomes are highlighted.

Addressing the management of atrial fibrillation - a systematic review of the role of dronedarone

BACKGROUND

Atrial fibrillation (AF) is the most common sustained arrhythmia. It occurs in 1%-2% of the general population and its prevalence increases with age. Dronedarone, a noniodinated benzofuran similar to amiodarone, was developed as an antiarrhythmic agent for patients with atrial fibrillation. The aim of our systematic review was to critically evaluate randomized controlled trials that compared treatment with dronedarone versus placebo or amiodarone in patients with atrial fibrillation.

METHODS

Electronic databases (MEDLINE, Embase, and Central) were searched up to November 2011 with no language restrictions. We included randomized controlled trials in which dronedarone was compared to placebo or other drugs in patients with AF. Internal and external validity was assessed.

RESULTS

We identified seven papers corresponding to eight randomized controlled trials. The DAFNE, EURIDIS/ADONIS, and ATHENA trials demonstrated a reduction of AF recurrence with dronedarone as compared to placebo in patients with nonpermanent AF. The DIONYSOS study showed that dronedarone is less effective for the prevention of recurrent AF but improved tolerability as compared to amiodarone. Considering patients with permanent AF, the ERATO trial showed that dronedarone had rate-control effects while the PALLAS study was stopped early since stroke, myocardial infarction, systemic embolism, or death from cardiovascular causes were significantly more frequent in subjects treated with dronedarone as compared to placebo. The ANDROMEDA trial included patients with recent hospitalization for heart failure and was terminated early because of excess of deaths in the dronedarone group.

CONCLUSION

Like most antiarrhythmic drugs, dronedarone reduces the recurrence of AF in patients with paroxysmal or persistent AF as compared to placebo. However, relapse rates in the first year of therapy are high. Moreover, dronedarone showed to be less effective than amiodarone. Finally, dronedarone should be avoided in patients with permanent AF and a high risk for cardiovascular events or severe congestive heart failure.

Antiarrhythmics for maintaining sinus rhythm after cardioversion of atrial fibrillation

BACKGROUND

Atrial fibrillation (AF) is the most frequent sustained arrhythmia. AF recurs frequently after restoration of normal sinus rhythm. Antiarrhythmic drugs have been widely used to prevent recurrence, but the effect of these drugs on mortality and other clinical outcomes is unclear.

OBJECTIVES

To determine, in patients who recovered sinus rhythm after AF, the effect of long-term treatment with antiarrhythmic drugs on death, stroke and embolism, adverse effects, pro-arrhythmia, and recurrence of AF.

SEARCH METHODS

We updated the searches of CENTRAL on The Cochrane Libary (Issue 1 of 4, 2010), MEDLINE (1950 to February 2010) and EMBASE (1966 to February 2010). The reference lists of retrieved articles, recent reviews and meta-analyses were checked.

SELECTION CRITERIA

Two independent reviewers selected randomised controlled trials comparing any antiarrhythmic with a control (no treatment, placebo or drugs for rate control) or with another antiarrhythmic, in adults who had AF and in whom sinus rhythm was restored. Post-operative AF was excluded.

DATA COLLECTION AND ANALYSIS

Two reviewers independently assessed quality and extracted data. Studies were pooled, if appropriate, using Peto odds ratio (OR). All results were calculated at one year of follow-up.

MAIN RESULTS

In this update, 11 new studies met inclusion criteria, making a total of 56 included studies, comprising 20,771 patients. Compared with controls, class IA drugs quinidine and disopyramide (OR 2.39, 95% confidence interval (95%CI) 1.03 to 5.59, number needed to harm (NNH) 109, 95%CI 34 to 4985) and sotalol (OR 2.47, 95%CI 1.2 to 5.05, NNH 166, 95%CI 61 to 1159) were associated with increased all-cause mortality. Other antiarrhythmics did not seem to modify mortality.Several class IA (disopyramide, quinidine), IC (flecainide, propafenone) and III (amiodarone, dofetilide, dronedarone, sotalol) drugs significantly reduced recurrence of AF (OR 0.19 to 0.70, number needed to treat (NNT) 3 to 16). Beta-blockers (metoprolol) also reduced significantly AF recurrence (OR 0.62, 95% CI 0.44 to 0.88, NNT 9).All analysed drugs increased withdrawals due to adverse affects and all but amiodarone, dronedarone and propafenone increased pro-arrhythmia. We could not analyse other outcomes because few original studies reported them.

AUTHORS' CONCLUSIONS

Several class IA, IC and III drugs, as well as class II (beta-blockers), are moderately effective in maintaining sinus rhythm after conversion of atrial fibrillation. However, they increase adverse events, including pro-arrhythmia, and some of them (disopyramide, quinidine and sotalol) may increase mortality. Possible benefits on clinically relevant outcomes (stroke, embolisms, heart failure) remain to be established.

Dronedarone-current status in management of atrial fibrillation

Atrial fibrillation (AF) is the most common of the serious cardiac rhythm disturbances and is responsible for substantial morbidity and mortality. Available drug therapy for AF has modest efficacy and is associated with the risk of life-threatening pro-arrhythmic complications. Dronedarone is a newer therapeutic agent with a structural resemblance to amiodarone and a better side effect profile. It is a multichannel blocker with antiadrenergic properties and has been evaluated in both rate and rhythm control strategies in the management of AF. In this review, we discuss the current role of dronedarone in the contemporary management of AF.

Catheter ablation for paroxysmal and persistent atrial fibrillation

BACKGROUND

Atrial fibrillation (AF) is the most common cardiac arrhythmia seen in cardiovascular departments. Treatments include medical interventions and catheter ablation. Due to uncertainties in medical therapies for AF, and the need to continue sinus rhythm, ablation has been recently considered as a viable alternative. Many new ablation methods based on pulmonary vein isolation (PVI) have been developed.

OBJECTIVES

The primary objective of this review was to assess the beneficial and harmful effects of catheter ablation (CA) in comparison with medical treatment in patients with paroxysmal and persistent AF. The secondary objective was to determine the best regimen of CA.

SEARCH METHODS

Searches were run on The Cochrane Central Register of Controlled Trials (CENTRAL) on The Cochrane Library Issue 3 2009, MEDLINE (1950 to August 2009), EMBASE (1980 to August 2009), the Chinese Biomedical Literature Database (1978 to August 2009) and the CKNI Chinese Paper Database (1994 to 2009) . Several journals published in Chinese were also handsearched.

SELECTION CRITERIA

Randomised controlled trials (RCTs) in people with paroxysmal and persistent AF treated by any type of CA method. Two reviewers independently selected the trials for inclusion.

DATA COLLECTION AND ANALYSIS

Assessments of risk of bias were performed by two reviewers, and relative risk (RR) and 95% confidence intervals (CI) were used for dichotomous variables. Meta-analysis were performed where appropriate.

MAIN RESULTS

A total of 32 RCTs (3,560 patients) were included. RCTs were small in size and of poor quality.CA compared with medical therapies: seven RCTs indicated that CA had a better effect in inhibiting recurrence of AF [RR 0.27; 95% CI 0.18, 0.41)] but there was significant heterogeneity. There was limited evidence to suggest that sinus rhythm was restored during CA (one small trial: RR 0.28, 95% CI 0.20-0.40), and at the end of follow-up (RR 1.87, 95% CI 1.31-2.67; I(2)=83%). There were no differences in mortality (RR, 0.50, 95% CI 0.04 to 5.65), fatal and non-fatal embolic complication (RR 1.01, 95% CI 0.18 to 5.68) or death from thrombo-embolic events (RR 3.04, 95% CI 0.13 to 73.43).Comparisons of different CAs; 25 RCTs compared CA of various kinds. Circumferential pulmonary vein ablation was better than segmental pulmonary vein ablation in improving symptoms of AF (p<=0.01) and in reducing the recurrence of AF (p<0.01). There is limited evidence to suggest which ablation method was the best.

AUTHORS' CONCLUSIONS

There is limited evidence to suggest that CA may be a better treatment option compared to medical therapies in the management of persistent AF. This review was also unable to recommend the best CA method.

Atrial fibrillation management, outcomes and predictors of stable disease in daily practice: prospective non-interventional study

BACKGROUND

We aimed to describe the current management of patients with atrial fibrillation (AF) by cardiologists, and to identify predicting factors for a stable disease course.

METHODS

2753 consecutive patients with ECG-confirmed AF in the previous 12 months were documented in a 1-year observational (non-interventional) study from 616 centers. Stable disease was defined as having neither AF related intervention nor change in antiarrhythmic therapy in the previous 12 months. Stepwise selection of parameters for multivariate regression was used to identify factors for stable AF.

RESULTS

At baseline, paroxysmal AF was reported in 33.5%, persistent in 26.7%, and permanent in 39.7%; rate control alone was the prevailing antiarrhythmic strategy (64.2%). Drugs for thromboembolic prevention were administered in 93.8%, with a clear predominance of oral anticoagulants (OAC), alone or in combination with antiplatelet drugs. Electrical or pharmacological conversions were reported in 23.6%. A total of 96 (3.5%) patients in the total cohort experienced stroke, 72 patients (2.6%) TIA, and 24 (0.9%) arterial embolism. 26% were hospitalized during follow-up (0.4 events per patient), and 9.4% developed incident heart failure (42% prevalence at follow-up). The rate of stable patients was 43.4%. In the multivariate model male gender, history of stroke, and permanent (vs. persistent) AF were associated with stable disease. Conversely, the factors chronic heart failure, impaired left ventricular function, rhythm-control (vs. other), OAC and antiplatelet therapy were significantly correlated with unstable disease.

CONCLUSIONS

The relatively low proportion of stable patients and in particular, the high hospitalization and stroke rate indicate difficulties in everyday management of patients with AF.

Symptomatic Bradycardia, Syncope, and Prolonged QTc Interval Associated with Dronedarone Therapy

Objective

To report a case of symptomatic bradycardia, prolonged QT interval, and syncope associated with dronedarone in a patient with atrial fibrillation who was maintained in sinus rhythm.

Case Summary

A 58-year-old man presented to the emergency department with a chief complaint of chest pain and “passing out.” Three months prior, dronedarone had been initiated for maintenance of sinus rhythm. An initial electrocardiogram (ECG) revealed normal sinus rhythm with a prolonged corrected QT (QTc) interval of 645 ms. Upon hospital admission, dronedarone was discontinued. Approximately 17 hours after hospitalization and 35 hours after the last ingested dronedarone dose, a repeat ECG revealed a QTc interval of 457 ms, and the patient reported symptomatic improvement. The patient was discharged home after a 3-day hospital stay without further event. The Naranjo Adverse Drug Reaction Probability Scale indicated a probable relationship between the patient's symptoms and dronedarone.

Discussion

Dronedarone is an antiarrhythmic drug that exhibits multiple mechanisms of action, including potassium, sodium, and calcium channel blockade, in addition to antiadrenegic activity. In clinical evaluations of dronedarone therapy, dronedarone was associated with a mean decrease in resting heart rate and potential to prolong the QT interval by 10 ms. These effects may result in clinically significant outcomes, as was observed in this patient.

Conclusions

This case of symptomatic bradycardia and prolonged QTc interval emphasizes the importance of monitoring the heart rate and ECG in patients prescribed dronedarone, particularly in those on concomitant drug therapy that may precipitate these events.

Costs and clinical consequences of suboptimal atrial fibrillation management

Atrial fibrillation (AF) places a considerable burden on the US health care system, society, and individual patients due to its associated morbidity, mortality, and reduced health-related quality of life. AF increases the risk of stroke, which often results in lengthy hospital stays, increased disability, and long-term care, all of which impact medical costs. An expected increase in the prevalence of AF and incidence of AF-related stroke underscores the need for optimal management of this disorder. Although AF treatment strategies have been proven effective in clinical trials, data show that patients still receive suboptimal treatment. Adherence to AF treatment guidelines will help to optimize treatment and reduce costs due to AF-associated events; new treatments for AF show promise for future reductions in disease and cost burden due to improved tolerability profiles. Additional research is necessary to compare treatment costs and outcomes of new versus existing agents; an immediate effort to optimize treatment based on existing evidence and guidelines is critical to reducing the burden of AF.

Cost considerations in the management of atrial fibrillation - impact of dronedarone

Atrial fibrillation (AF) is the most common sustained cardiac arrhythmia. It is associated with significant morbidity and mortality. At the societal level, AF carries an enormous cost. Strategies aimed at reducing AF morbidity and mortality and containing the associated fiscal burden are of paramount importance. This review will discuss AF treatment strategies and economics, focusing on the impact of dronedarone, a novel antiarrhythmic agent.

Amiodarone and the thyroid: a 2012 update

Amiodarone-induced thyroid dysfunction occurs in 15-20% of amiodarone-treated patients. Amiodarone-induced hypothyroidism (AIH) does not pose relevant problems, is easily controlled by L-thyroxine replacement, and does not require amiodarone withdrawal. Most frequently AIH develops in patients with chronic autoimmune thyroiditis. Amiodarone- induced thyrotoxicosis (AIT) is most frequently due to destructive thyroiditis (type 2 AIT) causing discharge of thyroid hormones from the damaged, but otherwise substantially normal gland. Less frequently AIT is a form of hyperthyroidism (type 1 AIT) caused by the iodine load in a diseased gland (nodular goiter, Graves' disease). A clearcut differentiation between the two main forms is not always possible, despite recent diagnostic advances. As a matter of fact, mixed or indefinite forms do exist, contributed to by both thyroid damage and increased thyroid hormone synthesis. Treatment of type 1 (and mixed forms) AIT is based on the use of thionamides, a short course of potassium perchlorate and, if treatment is not rapidly effective, oral glucocorticoids. Glucocorticoids are the first-line treatment for type 2 AIT. Amiodarone should be discontinued, if feasible from a cardiac standpoint. Continuation of amiodarone has recently been associated with a delayed restoration of euthyroidism and a higher chance of recurrence after glucocorticoid withdrawal. Whether amiodarone treatment can be safely reinstituted after restoration of euthyroidism is still unknown. In rare cases of AIT resistance to standard treatments, or when a rapid restoration of euthyroidism is advisable, total thyroidectomy represents a valid alternative. Radioiodine treatment is usually not feasible due to the low thyroidal iodine uptake.

Atrial fibrillation

The management of atrial fibrillation has evolved greatly in the past few years, and many areas have had substantial advances or developments. Recognition of the limitations of aspirin and the availability of new oral anticoagulant drugs that overcome the inherent drawbacks associated with warfarin will enable widespread application of effective thromboprophylaxis with oral anticoagulants. The emphasis on stroke risk stratification has shifted towards identification of so-called truly low-risk patients with atrial fibrillation who do not need antithrombotic therapy, whereas oral anticoagulation therapy should be considered in patients with one or more risk factors for stroke. New antiarrhythmic drugs, such as dronedarone and vernakalant, have provided some additional opportunities for rhythm control in atrial fibrillation. However, the management of the disorder is increasingly driven by symptoms. The availability of non-pharmacological approaches, such as ablation, has allowed additional options for the management of atrial fibrillation in patients who are unsuitable for or intolerant of drug approaches.

Dronedarone: an overview

Atrial fibrillation (AF) is the most common arrhythmia encountered in clinical practice. Until recently, a rhythm control strategy for AF has been limited by drug toxicity and side-effects, and landmark AF trials have shown that such a strategy is not superior to a rate control one. New antiarrhythmic drugs, free of undesired effects, would enhance the rhythm control strategy, with the possibility of sinus rhythm restoration and maintenance. One of the promising drugs recently approved for clinical use is dronedarone. This drug has amiodarone-like antiarrhythmic and electrophysiological properties, despite it having a modified structure and lacking an iodine moiety. Thus, dronedarone lacks amiodarone's organ toxicity (including adverse thyroid and pulmonary effects). The efficacy of dronedarone has been investigated in several clinical trials, proving its effect in the prevention of AF recurrence, rate control in paroxysmal/persistent and permanent AF, reduction of cardiovascular hospitalization or death from any cause, and others. Indirect comparisons with amiodarone, as well as one head-to-head study of the two drugs, indicate that the relative safety of dronedarone may be at a cost of its lower antiarrhythmic efficacy compared with amiodarone.

Managing atrial fibrillation in the elderly: critical appraisal of dronedarone

Atrial fibrillation is the most commonly seen arrhythmia in the geriatric population and is associated with increased cardiovascular morbidity and mortality. Treatment of the elderly with atrial fibrillation remains challenging for physicians, because this unique subpopulation is characterized by multiple comorbidities requiring chronic use of numerous medications, which can potentially lead to severe drug interactions. Furthermore, age-related changes in the cardiovascular system as well as other physiological changes result in altered drug pharmacokinetics. Dronedarone is a new drug recently approved for the treatment of arrhythmias, such as atrial fibrillation and/or atrial flutter. Dronedarone is a benzofuran amiodarone analog which lacks the iodine moiety and contains a methane sulfonyl group that decreases its lipophilicity. These differences in chemical structure are responsible for making dronedarone less toxic than amiodarone which, in turn, results in fewer side effects. Adverse events for dronedarone include gastrointestinal side effects and rash. No dosage adjustments are required for patients with renal impairment. However, the use of dronedarone is contraindicated in the presence of severe hepatic dysfunction.

Update on the clinical management of atrial fibrillation: guidelines and beyond

In clinical practice, atrial fibrillation (AF) is the most commonly encountered arrhythmia. With the aging of the US population, the number of patients with AF that physicians encounter will increase. Atrial fibrillation management involves a combination of rate- and rhythm-control strategies with thromboprophylaxis, a complicated endeavor given side effect profiles of treatments, patient comorbidities, and anticoagulation treatment requirements. Early treatment discontinuation and poor compliance with anticoagulation treatment are frequent and result in increased mortality, a 5-fold increased risk of ischemic stroke, decreased health-related quality of life, and decreased exercise capacity. In 2006, the American College of Cardiology/American Heart Association/European Society of Cardiology (ACC/AHA/ESC) provided guidelines for the management of patients with AF. Recently, the ACC Foundation, AHA, and Heart Rhythm Society released updates to these guidelines (January and February 2011). This article aims to assist physicians in improving the management of patients with AF by focusing on the main components of therapy as reflected in the guidelines, and by providing an update on new US Food and Drug Administration-approved treatments.

Atrial fibrillation: an epidemic in the elderly

Atrial fibrillation is the most common cardiac arrhythmia that increases in prevalence with age. As the general population grows older, general practitioners will more frequently see this disease in their clinic population. In order to most effectively treat these patients, physicians need to understand key issues, including the use of rhythm control versus ventricular rate control and how to reduce the risk of ischemic stroke. This article will review recent advancements in the understanding of the pathophysiology, management, stroke risk stratification and prevention of thromboembolic complications in atrial fibrillation.

Benefit-risk assessment of current antiarrhythmic drug therapy of atrial fibrillation

Over the last decade, several rhythm-versus rate-control trails in patients with atrial fibrillation (AF) have failed to demonstrate benefit of the rhythm control strategy with respect to mortality and morbidity. This had let to the guideline recommendation that antiarrhythmic drug therapy should be considered predominantly for symptomatic improvement of patients. Recent trails and meta-analyses have demonstrated that amiodarone is the most antiarrhythmic drug currently available. However, its use has been associated with many adverse effects. Currently, dronedarone is the only available antiarrhythmic drug which has shown a reduction in cardiovascular hospitalizations in medium-risk AF patients. However, the drug was associated with increased mortality in patients with recently decompensated heart failure. Hence, antiarrhythmic drug therapy has to be evaluated in patients with AF on an individual patients basis.

Dronedarone for the treatment of atrial fibrillation: a NICE single technology appraisal

The National Institute for Health and Clinical Excellence (NICE) invited the manufacturer of dronedarone (Multaq®, Sanofi-Aventis Limited, UK) to submit evidence on the clinical and cost effectiveness of the anti-arrhythmic drug (AAD) for the treatment of atrial fibrillation (AF) and atrial flutter, as part of the Institute's single technology appraisal (STA) process. The Centre for Reviews and Dissemination and the Centre for Health Economics, both at the University of York, were commissioned to act as the independent Evidence Review Group (ERG). This article provides a description of the company submission, the ERG review and NICE's subsequent decisions regarding the use of dronedarone within the UK NHS. The ERG review comprised a critique of the submitted evidence on the clinical effectiveness and cost effectiveness of dronedarone. The ERG examined the search strategy used to obtain relevant evidence, the selection of studies included in the assessment, outcome measures chosen and statistical methods employed. The ERG also validated the manufacturer's decision analytic model and used it to explore the robustness of the cost-effectiveness results to key assumptions. The main clinical effectiveness evidence supporting the use of dronedarone as a treatment for AF came from four randomized controlled trials. These trials were compared with a broader set of trials examining the effectiveness of other AADs for AF: amiodarone, sotalol and class 1c agents (flecainide and propafenone). The evidence suggested that all AADs decreased the recurrence of AF but dronedarone had the smallest effect. A mixed treatment comparison analysis of the trials showed that dronedarone was associated with a lower risk of all-cause mortality than other AADs, but this was highly uncertain. There was limited evidence to assess the effect of dronedarone on stroke, and no statistically significant differences between dronedarone and other AADs were found for treatment discontinuation. From the evidence presented by the manufacturer, dronedarone appeared highly cost effective in each of the population groups examined compared with using standard baseline therapy alone as first-line treatment, or compared with sotalol or amiodarone as first-line AAD, with incremental cost-effectiveness ratios (ICERs) well below £20,000 per QALY gained. The ICER for dronedarone relative to class 1c agents was around £19,000 per QALY. Although the evidence presented by the manufacturer indicated that dronedarone was cost effective, the estimates of treatment effect relative to other AADs and safety in the longer term were highly uncertain. The NICE Appraisal Committee in its preliminary guidance did not recommend the use of dronedarone for AF. However, following the response from a large number of consultees and commentators, NICE revised its preliminary guidance to allow the use of the drug in a specific subgroup of AF patients with additional cardiovascular risk factors.

Celivarone for maintenance of sinus rhythm and conversion of atrial fibrillation/flutter

INTRODUCTION

Celivarone, a new noniodinated benzofuran derivative pharmacologically related to dronedarone and amiodarone, has been shown to have antiarrhythmic properties at a molecular level. The purpose of the 2 trials presented here (MAIA and CORYFEE) was to assess celivarone efficacy in the maintenance of sinus rhythm postcardioversion and for the conversion of atrial fibrillation (AF)/atrial flutter (AFL).

METHODS AND RESULTS

In the MAIA trial, 673 patients with AF/AFL recently converted to sinus rhythm were randomly assigned to receive 50, 100, 200, or 300 mg once-daily dosing of celivarone; 200 mg daily of amiodarone preceded by a loading dose of 600 mg for 10 days; or placebo. At 3 months' follow up, no significant difference was observed in time to AF/AFL relapse among the various celivarone groups and placebo. However, fewer symptomatic AF/AFL recurrences were observed in the lower-dose celivarone groups (26.6% for celivarone 50 mg [P = 0.022] and 25.2% for celivarone 100 mg [P = 0.018] vs 40.5% for placebo at 90 days). Fewer adverse events were observed with the use of celivarone and placebo than amiodarone. In the CORYFEE study, 150 patients with AF/AFL were randomly assigned to once-daily celivarone dosing of 300 or 600 mg, or placebo, for a 2-day treatment period. There was no significant difference in the rate of spontaneous conversion to sinus rhythm between the treatment and control groups.

CONCLUSIONS

In these studies, celivarone does not appear to be efficacious in the maintenance of sinus rhythm in AF/AFL patients or for the conversion of AF/AFL patients. 

Mitochondrial oxidative stress and respiratory chain dysfunction account for liver toxicity during amiodarone but not dronedarone administration

The role played by oxidative stress in amiodarone-induced mitochondrial toxicity is debated. Dronedarone shows pharmacological properties similar to those of amiodarone but several differences in terms of toxicity. In this study, we analyzed the effects of the two drugs on liver mitochondrial function by administering an equivalent human dose to a rat model. Amiodarone increased mitochondrial H(2)O(2) synthesis, which in turn induced cardiolipin peroxidation. Moreover, amiodarone inhibited Complex I activity and uncoupled oxidative phosphorylation, leading to a reduction in the hepatic ATP content. We also observed a modification of membrane phospholipid composition after amiodarone administration. N-acetylcysteine completely prevented such effects. Although dronedarone shares with amiodarone the capacity to induce uncoupling of oxidative phosphorylation, it did not show any of the oxidative effects and did not impair mitochondrial bioenergetics. Our data provide important insights into the mechanism of mitochondrial toxicity induced by amiodarone. These results may greatly influence the clinical application and toxicity management of these two antiarrhythmic drugs.

Dronedarone in high-risk permanent atrial fibrillation

BACKGROUND

Dronedarone restores sinus rhythm and reduces hospitalization or death in intermittent atrial fibrillation. It also lowers heart rate and blood pressure and has antiadrenergic and potential ventricular antiarrhythmic effects. We hypothesized that dronedarone would reduce major vascular events in high-risk permanent atrial fibrillation.

METHODS

We assigned patients who were at least 65 years of age with at least a 6-month history of permanent atrial fibrillation and risk factors for major vascular events to receive dronedarone or placebo. The first coprimary outcome was stroke, myocardial infarction, systemic embolism, or death from cardiovascular causes. The second coprimary outcome was unplanned hospitalization for a cardiovascular cause or death.

RESULTS

After the enrollment of 3236 patients, the study was stopped for safety reasons. The first coprimary outcome occurred in 43 patients receiving dronedarone and 19 receiving placebo (hazard ratio, 2.29; 95% confidence interval [CI], 1.34 to 3.94; P=0.002). There were 21 deaths from cardiovascular causes in the dronedarone group and 10 in the placebo group (hazard ratio, 2.11; 95% CI, 1.00 to 4.49; P=0.046), including death from arrhythmia in 13 patients and 4 patients, respectively (hazard ratio, 3.26; 95% CI, 1.06 to 10.00; P=0.03). Stroke occurred in 23 patients in the dronedarone group and 10 in the placebo group (hazard ratio, 2.32; 95% CI, 1.11 to 4.88; P=0.02). Hospitalization for heart failure occurred in 43 patients in the dronedarone group and 24 in the placebo group (hazard ratio, 1.81; 95% CI, 1.10 to 2.99; P=0.02).

CONCLUSIONS

Dronedarone increased rates of heart failure, stroke, and death from cardiovascular causes in patients with permanent atrial fibrillation who were at risk for major vascular events. Our data show that this drug should not be used in such patients. (Funded by Sanofi-Aventis; PALLAS ClinicalTrials.gov number, NCT01151137.).

The management of patients with atrial fibrillation and dronedarone's place in therapy

The pharmacologic management of atrial fibrillation (AF) includes rate and rhythm control strategies. Antiarrhythmic agents (eg, amiodarone, flecainide, and propafenone) are limited by serious toxicities (including proarrhythmic effects and pulmonary toxicity), which may lead to a reduced net clinical efficacy of rhythm control strategies. Dronedarone, a new antiarrhythmic agent, is effective in the maintenance of sinus rhythm. Dronedarone has also been shown to reduce ventricular rate and the incidence of hospitalization due to cardiovascular events. Dronedarone is recommended by the 2011 American College of Cardiology Foundation/American Heart Association/Heart Rhythm Society guidelines update for the management of AF patients with no or minimal heart disease, coronary artery disease, and hypertension with no left ventricular hypertrophy. Dronedarone is contraindicated in patients with New York Heart Association (NYHA) class IV heart failure or NYHA class II-III heart failure with a recent decompensation requiring hospitalization or referral to a specialized heart failure clinic.

Rationale and current perspective for early rhythm control therapy in atrial fibrillation

Atrial fibrillation (AF) is the most common sustained arrhythmia and an important source for mortality and morbidity on a population level. Despite the clear association between AF and death, stroke, and other cardiovascular events, there is no evidence that rhythm control treatment improves outcome in AF patients. The poor outcome of rhythm control relates to the severity of the atrial substrate for AF not only due to the underlying atrial remodelling process but also due to the poor efficacy and adverse events of the currently available ion-channel antiarrhythmic drugs and ablation techniques. Data suggest, however, an association between sinus rhythm maintenance and improved survival. Hypothetically, sinus rhythm may also lead to a lower risk of stroke and heart failure. The presence of AF, thus, seems one of the modifiable factors associated with death and cardiovascular morbidity in AF patients. Patients with a short history of AF and the underlying heart disease have not been studied before. It is fair to assume that abolishment of AF in these patients is more successful and possibly also safer, which could translate into a prognostic benefit of early rhythm control therapy. Several trials are now investigating whether aggressive early rhythm control therapy can reduce cardiovascular morbidity and mortality and increase maintenance of sinus rhythm. In the present paper we describe the background of these studies and provide some information on their design.

Safety and efficacy of dronedarone in the treatment of atrial fibrillation/flutter

Dronedarone is an amiodarone analog but differs structurally from amiodarone in that the iodine moiety was removed and a methane-sulfonyl group was added. These modifications reduced thyroid and other end-organ adverse effects and makes dronedarone less lipophilic, shortening its half-life. Dronedarone has been shown to prevent atrial fibrillation/flutter (AF/AFl) recurrences in several multi-center trials. In addition to its rhythm control properties, dronedarone has rate control properties and slows the ventricular response during AF. Dronedarone is approved in Europe for rhythm and rate control indications. In patients with decompensated heart failure, dronedarone treatment increased mortality and cardiovascular hospitalizations. However, when dronedarone was used in elderly high risk AF/AFl patients excluding such high risk heart failure, cardiovascular hospitalizations were significantly reduced and the drug was approved in the USA for this indication in 2009 by the Food and Drug Administration. Updated guidelines suggest dronedarone as a front-line antiarrhythmic in many patients with AF/Fl but caution that the drug should not be used in patients with advanced heart failure. In addition, the recent results of the PALLAS trial suggest that dronedarone should not be used in the long-term treatment of patients with permanent AF.

Rate vs rhythm control in patients with atrial fibrillation and heart failure: a systematic review and meta-analysis of randomised controlled trials

BACKGROUND

Atrial fibrillation (AF) is a common arrhythmia that can promote or worsen heart failure (HF). Our purpose was to compare the effects of rate and rhythm control in patients with atrial fibrillation and heart failure.

METHODS

We developed a systematic search in August 2010 through CENTRAL and MEDLINE databases to identify randomised controlled trials (RCTs) comparing rate control with rhythm control in patients with both AF and HF. We analysed mortality, hospitalisations, stroke/thromboembolic events, quality of life, and drugs adverse events. Relative risks (RR) and 95% confidence intervals (95% CI) were calculated for mortality and hospitalisations. The remaining outcomes were analysed qualitatively.

RESULTS

Four RCTs with a total of 2486 patients with atrial fibrillation and heart failure were identified. Mortality and stroke/thromboembolic events were not significantly different in rate and rhythm control arms [RR 1.03; 95% CI: 0.90-1.17] and [RR 1.09; 95% CI: 0.61-1.96], respectively. Hospitalisations were less frequent with rate control than with rhythm control [RR 0.92; 95% CI: 0.86-0.98; p=0.008], in 3 studies involving 2425 patients. Number needed to treat to prevent one hospitalisation was 19 patients.

CONCLUSIONS

In patients with AF and HF, rate control compared with rhythm control showed inferior risk of hospitalisation.

Evaluation of dronedarone use in the US patient population between 2009 and 2010: a descriptive study using a claims database

BACKGROUND

The utilization pattern of dronedarone was unknown, especially regarding prescribers' compliance with the product's prescribing information (PI) following its availability and the implementation of the Food and Drug Administration-approved risk evaluation and mitigation strategy for the drug in the United States.

OBJECTIVE

This study was designed to evaluate the dronedarone prescribers' adherence to PI regarding the following contraindications: (1) patients with heart failure (HF) with a recent decompensation requiring hospitalization or referral to a specialist, (2) concomitant use of potent CYP3A4 inhibitors, and (3) concomitant use of QT-prolonging drugs.

METHODS

Patients prescribed dronedarone between July 2009 and August 2010 were identified through LabRx. The following rates surrounding dronedarone use were examined: (1) atrial fibrillation or atrial flutter in the past year, (2) worsening or hospitalization for HF within the month before prescription, and (3) concomitant prescription of potent CYP3A4 inhibitors and concomitant prescription of QT-prolonging drugs within the following month.

RESULTS

A total of 4595 dronedarone prescriptions were filled by 1820 patients. More than 94% of the participants had ≥1 diagnosis of atrial fibrillation or atrial flutter in the previous year. Worsening of or hospitalization for HF was found in 61 (3.4%) patients within the month before receiving dronedarone, including 18 patients with HF as the primary cause for hospitalization. Potent CYP3A4 inhibitors were prescribed to 10 (0.6%) patients within a month following dronedarone initiation, 6 of whom received them for topical use only. QT-prolonging drugs were prescribed to 67 (3.7%) patients within a month following dronedarone initiation, among which >90% were other antiarrhythmics.

CONCLUSIONS

Dronedarone was used mostly in compliance with PI and risk evaluation and mitigation strategy in the studied population. In the LabRx database, dronedarone was commonly dispensed to patients with cardiovascular risk factors and rarely dispensed to patients with contraindications such as worsening HF or hospitalization for HF or with concomitant prescriptions of potent CYP3A4 inhibitors, QT-prolonging drugs, or both.