Effects of statin therapy on preventing atrial fibrillation in coronary disease and heart failure

Redox State in Atrial Fibrillation Pathogenesis and Relevant Therapeutic Approaches

BACKGROUND

Myocardial redox state is a critical determinant of atrial biology, regulating cardiomyocyte apoptosis, ion channel function, and cardiac hypertrophy/fibrosis and function. Nevertheless, it remains unclear whether the targeting of atrial redox state is a rational therapeutic strategy for atrial fibrillation prevention.

OBJECTIVE

To review the role of atrial redox state and anti-oxidant therapies in atrial fibrillation.

METHOD

Published literature in Medline was searched for experimental and clinical evidence linking myocardial redox state with atrial fibrillation pathogenesis as well as studies looking into the role of redoxtargeting therapies in the prevention of atrial fibrillation.

RESULTS

Data from animal models have shown that altered myocardial nitroso-redox balance and NADPH oxidases activity are causally involved in the pathogenesis of atrial fibrillation. Similarly experimental animal data supports that increased reactive oxygen / nitrogen species formation in the atrial tissue is associated with altered electrophysiological properties of atrial myocytes and electrical remodeling, favoring atrial fibrillation development. In humans, randomized clinical studies using redox-related therapeutic approaches (e.g. statins or antioxidant agents) have not documented any benefits in the prevention of atrial fibrillation development (mainly post-operative atrial fibrillation risk).

CONCLUSION

Despite strong experimental and translational data supporting the role of atrial redox state in atrial fibrillation pathogenesis, such mechanistic evidence has not been translated to clinical benefits in atrial fibrillation risk in randomized clinical studies using redox-related therapies.

Antiarrhythmic Drug Therapy for Atrial Fibrillation

Atrial fibrillation (AF) is the most frequently encountered arrhythmia. Prevalence increases with advancing age and so as its associated comorbidities, like heart failure. Choice of pharmacologic therapy depends on whether the goal of treatment is maintaining sinus rhythm or tolerating AF with adequate control of ventricular rates. Antiarrhythmic therapy and conversion of AF into sinus rhythm comes with the side effect profile, and we should select best antiarrhythmic therapy, individualized to the patient. New antiarrhythmic drugs are being tested in clinical trials. Drugs that target remodeling and inflammation are being tested for their use as prevention of AF or as upstream therapy.

Discontinuation of Dofetilide From QT Prolongation and Ventricular Tachycardia in the Real World

OBJECTIVES

The purpose of this study was to determine the incidence and correlates of QT prolongation or ventricular tachycardia (VT) resulting in discontinuation of dofetilide in a real-world setting.

BACKGROUND

Dofetilide is a class III antiarrhythmic agent approved for achieving and maintaining sinus rhythm in patients with symptomatic atrial fibrillation. Because of a risk of QT prolongation and VT, patients starting dofetilide need to be hospitalized for 3 days to closely monitor telemetry and electrocardiography. In large clinical trials, <3% of patients had to discontinue dofetilide because of QT prolongation, but data from real-world experience are lacking.

METHODS

We examined 114 consecutive patients with atrial fibrillation who were hospitalized for starting dofetilide at the Minneapolis Veterans Affairs Health Care System from 2011 to 2014.

RESULTS

The mean age of the patients was 64 ± 8 years. Dofetilide was discontinued in 22 (19%) patients because of QT prolongation (17%) or VT (2%). A total of 32 (28%) patients were taking other QT-prolonging drugs. Of these, 10 (31%) had to discontinue dofetilide versus 12 (15%) of the 82 patients who were not taking any other QT-prolonging drugs (p = 0.04). Patients who were taking concomitant QT-prolonging drugs were 1.9 times more likely to discontinue dofetilide (95% confidence interval: 1.1 to 3.4; p = 0.04) compared with those who were not taking any other QT-prolonging drugs.

CONCLUSIONS

The incidence of QT prolongation or VT that lead to discontinuation of dofetilide is remarkably higher in the real-world setting than in clinical trials. Concomitant use of other QT-prolonging drugs was associated with discontinuation of dofetilide.

Clinical update on the management of atrial fibrillation

Atrial fibrillation (AF) is a cardiac arrhythmia associated with significant morbidity and mortality, affecting more than 3 million people in the United States and 1-2% of the population worldwide. Its estimated prevalence is expected to double within the next 50 years. During the past decade, there have been significant advances in the treatment of AF. Studies have demonstrated that a rate control strategy, with a target resting heart rate between 80 and 100 beats/minute, is recommended over rhythm control in the vast majority of patients. The CHA2 DS2 ≥ (congestive heart failure, hypertension, age ≥ 65 yrs, diabetes mellitus, stroke or transient ischemic attack, vascular disease, female gender) scoring system is a potentially useful stroke risk stratification tool that incorporates additional risk factors to the commonly used CHADS2 (congestive heart failure, hypertension, age ≥ 75 years, diabetes mellitus, stroke transient ischemic attack) scoring tool. Similarly, a convenient scheme, termed HAS-BLED (hypertension, abnormal renal/liver function, stroke, bleeding history or predisposition, labile international normalized ratio, elderly, drugs/alcohol concomitantly), to assess bleeding risk has emerged that may be useful in select patients. Furthermore, new antithrombotic strategies have been developed as potential alternatives to warfarin, including dual-antiplatelet therapy with clopidogrel plus aspirin and the development of new oral anticoagulants such as dabigatran, rivaroxaban, and apixaban. Vernakalant has emerged as another potential option for pharmacologic conversion of AF, whereas recent trials have better defined the role of dronedarone in the maintenance of sinus rhythm. Finally, catheter ablation represents another alternative to manage AF, whereas upstream therapy with inhibitors of the renin-angiotensin-aldosterone system, statins, and polyunsaturated fatty acids could potentially prevent the occurrence of AF. Despite substantial progress in the management of AF, significant uncertainty surrounds the optimal treatment of this condition.

Targeting inflammation and oxidative stress in atrial fibrillation: role of 3-hydroxy-3-methylglutaryl-coenzyme a reductase inhibition with statins

SIGNIFICANCE

Atrial fibrillation (AF) is a burgeoning health-care problem, and the currently available therapeutic armamentarium is barely efficient. Experimental and clinical evidence implicates inflammation and myocardial oxidative stress in the pathogenesis of AF.

RECENT ADVANCES

Local and systemic inflammation has been found to both precede and follow the new onset of AF, and NOX2-dependent generation of reactive oxygen species in human right atrial samples has been independently associated with the occurrence of AF in the postoperative period in patients undergoing cardiac surgery. Anti-inflammatory and antioxidant agents can prevent atrial electrical remodeling in animal models of atrial tachypacing and the new onset of AF after cardiac surgery, suggesting a causal relationship between inflammation/oxidative stress and the atrial substrate that supports AF.

CRITICAL ISSUES

Statin therapy, by redressing the myocardial nitroso-redox balance and reducing inflammation, has emerged as a potentially effective strategy for the prevention of AF. Evidence indicates that statins prevent AF-induced electrical remodeling in animal models of atrial tachypacing and may reduce the new onset of AF after cardiac surgery. However, whether statins have antiarrhythmic properties in humans has yet to be conclusively demonstrated, as data from randomized controlled trials specifically addressing the relevance of statin therapy for the primary and secondary prevention of AF remain scanty.

FUTURE DIRECTIONS

A better understanding of the mechanisms underpinning the putative antiarrhythmic effects of statins may afford tailoring AF treatment to specific clinical settings and patient's subgroups. Large-scale randomized clinical trials are needed to support the indication of statin therapy solely on the basis of AF prevention.

Statins therapy can reduce the risk of atrial fibrillation in patients with acute coronary syndrome: a meta-analysis

BACKGROUND

It is a controversy whether statins therapy could be beneficial for the occurrence of atrial fibrillation (AF) in acute coronary syndrome (ACS). To clarify this problem, we performed a meta-analysis with the currently published literatures.

METHODS

The electronic databases were searched to obtain relevant trials which met the inclusion criteria through October 2011. Two authors independently read the trials and extracted the related information from the included studies. Either fixed-effects models or random-effects models were assumed to calculate the overall combined risk estimates according to I(2 )statistic. Sensitivity analysis was conducted by omitting one study in each turn, and publication bias was evaluated using Begg's and Egger's test.

RESULTS

Six studies were eligible to inclusion criteria, of the six studies, 161305 patients were included in this meta-analysis, 77920 (48.31%) patients had taken the statins therapy, 83385 (51.69%) patients had taken non-statins therapy. Four studies had investigated the effect of statins therapy on occurrence of new-onset AF in ACS patients, another two had described the association between statins therapy and occurrence of AF in ACS patients with AF in baseline. The occurrence of AF was reduced 35% in statins therapy group compared to that in non-statins group (95% confident interval: 0.55-0.77, P<0.0001), and the effect of statins therapy seemed more beneficial for new-onset AF (RR=0.59, 95%CI: 0.48-0.73, p=0.096) than secondary prevention of AF (RR=0.70, 95%CI: 0.43-1.14, p=0.085). There was no publication bias according to the Begg's and Egger's test (Begg, p=0.71; Egger, p=0.73).

CONCLUSION

Statins therapy could reduce the risk of atrial fibrillation in patients with ACS.

The role of statin therapy in the prevention of atrial fibrillation: a meta-analysis of randomized controlled trials

WHAT IS ALREADY KNOWN ABOUT THIS SUBJECT

Atrial fibrillation (AF) is the most common clinically significant cardiac arrhythmia, and AF is associated with relatively higher all-cause mortality in both men and women. However, there are limited treatment options for AF. Statins are hypothesized to have a benefit against arrhythmias in addition to well-established secondary prevention benefit for atherosclerotic coronary artery disease, yet the data are inconsistent

WHAT THIS STUDY ADDS

Statin therapy was significantly associated with a decreased risk of incidence or recurrence of AF. The benefit of statin therapy seemed more markedly in secondary prevention than primary prevention. These results provided some evidence for the benefit of statins beyond their lipid-lowering activity

AIMS

The use of statins has been suggested to protect against atrial fibrillation (AF) in some clinical observational and experimental studies but has remained inadequately explored. This study was designed to examine whether statins can reduce the risk of AF.

METHODS

Meta-analysis of randomized, controlled trials with use of statins on incidence or recurrence of AF was performed.

RESULTS

Twenty studies with 23,577 patients were included in the analysis. Seven studies investigated the use of statins in patients with AF, 11 studies investigated the primary prevention of statins in patients without AF, and two studies investigated mixed populations of patients. The incidence or recurrence of AF occurred in 1543 patients. Overall, statin therapy was significantly associated with a decreased risk of AF compared with control (odds ratio 0.49, 95% confidence interval 0.37-0.65; P < 0.00001). A beneficial effect was found in the atorvastatin subgroup and the simvastatin subgroup, but not in the pravastatin subgroup or the rosuvastatin subgroup. The benefit of statin therapy appeared to be more pronounced in secondary prevention (odds ratio 0.34, 95% confidence interval 0.18-0.64; P < 0.0008) than in primary prevention (odds ratio 0.54, 95% confidence interval 0.40-0.74; P < 0.0001).

CONCLUSIONS

Statin therapy was significantly associated with a decreased risk of incidence or recurrence of AF. Heterogeneity was explained by differences in statin types, patient populations and surgery types. The benefit of statin therapy seemed more pronounced in secondary than in primary prevention.

The preventive effect of statin therapy on new-onset and recurrent atrial fibrillation in patients not undergoing invasive cardiac interventions: a systematic review and meta-analysis

BACKGROUND

Previous meta-analyses suggest that pre-procedural use of statin therapy may reduce atrial fibrillation (AF) following invasive cardiac interventions (coronary artery by-pass grafting and percutaneous coronary intervention). However, the current evidence on the benefit of statins unrelated to invasive cardiac interventions has not been clarified systematically.

METHODS

Through a systematic literature search, trials examining the effect of statin therapy on AF were selected. Trials using statins before any percutaneous or surgical cardiac interventions were excluded.

RESULTS

The search identified 11 randomized and 16 observational eligible studies, totaling 106,640 patients receiving statin therapy and 129,305 serving as controls. Fourteen studies investigated the effect of statins on new-onset AF, 13 studies investigated the effect of statins on recurrent AF and one in both new-onset and recurrent AF. In the statin versus control group the mean age was 60.7 ± 8.3 versus 68.6 ± 6.2 years and females comprised 8.4% versus 10.3%. Statin therapy was associated with significant reduction of AF (Risk ratio (RR): 0.81 [95% confidence interval (CI): 0.80-0.83], p<0.001) combining all studies. Assessing exclusively randomized trials, statin therapy showed no significant risk reduction (RR: 0.97 [95%CI: 0.90-1.05], p=0.509), heterogeneity p>0.05. Assessing exclusively observational studies the risk reduction of new-onset AF was 12% (RR: 0.88 [95%CI: 0.85-0.91], p<0.001) and recurrent AF 15% (RR: 0.85 [95%CI: 0.80-0.90], p<0.001), heterogeneity p<0.001.

CONCLUSION

The hitherto published randomized clinical trials do not support a beneficial effect of statins on AF in patients not undergoing invasive cardiac interventions. This is in contrast to the results of observational and interventional studies.

Effect of lipid lowering on new-onset atrial fibrillation in patients with asymptomatic aortic stenosis: the Simvastatin and Ezetimibe in Aortic Stenosis (SEAS) study

BACKGROUND

Lipid-lowering drugs, particularly statins, have anti-inflammatory and antioxidant properties that may prevent atrial fibrillation (AF). This effect has not been investigated on new-onset AF in asymptomatic patients with aortic stenosis (AS).

METHODS

Asymptomatic patients with mild-to-moderate AS (n = 1,421) were randomized (1:1) to double-blind simvastatin 40 mg and ezetimibe 10 mg combination or placebo and followed up for a mean of 4.3 years. The primary end point was the time to new-onset AF adjudicated by 12-lead electrocardiogram at a core laboratory reading center. Secondary outcomes were the correlates of new-onset AF with nonfatal nonhemorrhagic stroke and a combined end point of AS-related events.

RESULTS

During the course of the study, new-onset AF was detected in 85 (6%) patients (14.2/1,000 person-years of follow-up). At baseline, patients who developed AF were, compared with those remaining in sinus rhythm, older and had a higher left ventricular mass index a smaller aortic valve area index. Treatment with simvastatin and ezetimibe was not associated with less new-onset AF (odds ratio 0.89 [95% CI 0.57-1.97], P = .717). In contrast, age (hazard ratio [HR] 1.07 [95% CI 1.05-1.10], P < .001) and left ventricular mass index (HR 1.01 [95% CI 1.01-1.02], P < .001) were independent predictors of new-onset AF. The occurrence of new-onset AF was independently associated with 2-fold higher risk of AS-related outcomes (HR 1.65 [95% CI 1.02-2.66], P = .04) and 4-fold higher risk of nonfatal nonhemorrhagic stroke (HR 4.04 [95% CI 1.18-13.82], P = .03).

CONCLUSIONS

Simvastatin and ezetimibe were not associated with less new-onset AF. Older age and greater left ventricular mass index were independent predictors of AF development. New-onset AF was associated with a worsening of prognosis.

Long-term efficacy of upstream therapy with lipophilic or hydrophilic statins on antiarrhythmic drugs in patients with paroxysmal atrial fibrillation: comparison between atorvastatin and pravastatin

There is little information available on the benefits of selection of statins as upstream therapy for the prevention of paroxysmal atrial fibrillation (AF). We compared the efficacy and safety of atorvastatin (A-group, n = 43) and pravastatin (P-group, n = 41) as upstream therapy in patients with paroxysmal AF and dyslipidemia. A total of 84 patients (45 men, mean age, 66 ± 9 years, mean follow-up, 49 ± 32 months) were retrospectively assigned to receive atorvastatin (n = 41;10 mg/day) or pravastatin (n = 43 ; 10 mg/day). Survival rates free from AF recurrence at 1, 6, 12, and 24 months were 93%, 74%, 60%, and 53% in A-group, and 88%, 49%, 37%, and 29%, respectively, in P-group (P = 0.029, A-group versus P-group). Survival rates free from conversion to permanent AF at 12, 36, 60, and 90 months were 100%, 100%, 98%, and 95% in A-group, and 100%, 95%, 88%, and 83%, respectively, in P-group (P = 0.063, A-group versus P-group). Using a logistic regression model, atorvastatin was found to be associated with a significantly reduced risk of AF recurrence in comparison to pravastatin (unadjusted odds ratio [OR] = 0.27, 95% confidence interval 0.11-0.68, P = 0.005). This association remained significant after adjustment for potentially confounding variables (OR = 0.26, 95% CI 0.08-0.86, P = 0.027). Using a logistic regression model, atorvastatin was not associated with a significantly reduced risk of converting to permanent AF in comparison to pravastatin (unadjusted OR = 0.29, 95% CI 0.05-1.50, P = 0.138), but this association did show a significant difference after adjustment for potentially confounding variables in a multivariate model (OR = 0.08, 95% CI 0.06-0.96, P = 0.046). Adverse effects requiring discontinuation of statins were observed in 1 case (2%, myalgia) in A-group, and 1 case (2%, elevation in CPK level ≥ 500 IU/L) in P-group, respectively (P = NS, A-group versus P-group). Atorvastatin, a lipophilic statin, was considered to be more effective in preventing recurrence of paroxysmal AF and conversion to permanent AF than pravastatin, a hydrophilic statin.

Upstream therapies for management of atrial fibrillation: review of clinical evidence and implications for European Society of Cardiology guidelines. Part I: primary prevention

Atrial fibrillation (AF) is associated with significant morbidity and mortality. It is also a progressive disease secondary to continuous structural remodelling of the atria due to AF itself, to changes associated with ageing, and to deterioration of underlying heart disease. Current management aims at preventing the recurrence of AF and its consequences (secondary prevention) and includes risk assessment and prevention of stroke, ventricular rate control, and rhythm control therapies including antiarrhythmic drugs and catheter or surgical ablation. The concept of primary prevention of AF with interventions targeting the development of substrate and modifying risk factors for AF has emerged as a result of recent experiments that suggested novel targets for mechanism-based therapies. Upstream therapy refers to the use of non-antiarrhythmic drugs that modify the atrial substrate- or target-specific mechanisms of AF to prevent the occurrence or recurrence of the arrhythmia. Such agents include angiotensin-converting enzyme inhibitors (ACEIs), angiotensin receptor blockers (ARBs), statins, n-3 (ω-3) polyunsaturated fatty acids, and possibly corticosteroids. Animal experiments have compellingly demonstrated the protective effect of these agents against electrical and structural atrial remodelling in association with AF. The key targets of upstream therapy are structural changes in the atria, such as fibrosis, hypertrophy, inflammation, and oxidative stress, but direct and indirect effects on atrial ion channels, gap junctions, and calcium handling are also applied. Although there have been no formal randomized controlled studies (RCTs) in the primary prevention setting, retrospective analyses and reports from the studies in which AF was a pre-specified secondary endpoint have shown a sustained reduction in new-onset AF with ACEIs and ARBs in patients with significant underlying heart disease (e.g. left ventricular dysfunction and hypertrophy), and in the incidence of AF after cardiac surgery in patients treated with statins. In the secondary prevention setting, the results with upstream therapies are significantly less encouraging. Although the results of hypothesis-generating small clinical studies or retrospective analyses in selected patient categories have been positive, larger prospective RCTs have yielded controversial, mostly negative, results. Notably, the controversy exists on whether upstream therapy may impact mortality and major non-fatal cardiovascular events in patients with AF. This has been addressed in retrospective analyses and large prospective RCTs, but the results remain inconclusive pending further reports. This review provides a contemporary evidence-based insight into the role of upstream therapies in primary (Part I) and secondary (Part II) prevention of AF.

Pleiotropic effects of statins: evidence for benefits beyond LDL-cholesterol lowering

Evidence is mounting that 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitors (statins) have a number of pleiotropic effects over and above their lipid-lowering properties in patients with cardiovascular disease and heart failure. In addition to lowering low-density lipoprotein cholesterol and triglyceride levels, several studies have shown statins to improve survival and reduce the risk of major cardiovascular events in patients without established cardiovascular disease but with cardiovascular risk factors. Statins have also been shown to have beneficial effects, including a reduction in all-cause mortality, in patients with ischemic and non-ischemic congestive heart failure, and have been associated with a reduced incidence of atrial fibrillation. Furthermore, statins have been associated with improvements in renal function in patients with pre-existing renal disease or the prevention of new-onset renal dysfunction, as well as improvements in lung function in patients with chronic obstructive pulmonary disease or age-related decline in lung function. The pleiotropic effects of statins appear to result from improvements in endothelial function, a reduction in inflammatory mediators, a decline in the development of atheroma through the stabilization of atheromatous plaques, and the inhibition of cardiac hypertrophy through an antioxidant mechanism. Long-term statin use may reduce morbidity and mortality rates in a broad range of patients, and most patients at high risk of cardiovascular disease may benefit from statin treatment; however, further data are required to demonstrate conclusively whether these trends are truly independent of the lipid-lowering effects of statins.

High-dose atorvastatin and risk of atrial fibrillation in patients with prior stroke or transient ischemic attack: analysis of the Stroke Prevention by Aggressive Reduction in Cholesterol Levels (SPARCL) trial

BACKGROUND

Observational analyses and short-term randomized trials have suggested that statins reduce occurrence or recurrence of atrial fibrillation (AF). We tested the hypothesis that long-term treatment with high-dose atorvastatin reduces occurrence of AF in patients with prior stroke or transient ischemic attack.

METHODS

We examined development of new AF in the SPARCL trial that compared atorvastatin 80 mg daily with placebo in 4,731 patients with prior stroke or transient ischemic attack. Patients who had chronic or paroxysmal AF or were taking medications for treatment or prophylaxis of AF at the time of enrollment were excluded. Atrial fibrillation was identified from electrocardiograms submitted to a blinded central electrocardiographic laboratory and from investigators' adverse event reports.

RESULTS

Patients were followed up for a median of 4.8 years, corresponding to >20,000 patient-years of observation with a median of 5 electrocardiograms per patient. The primary efficacy measure, the time from randomization to first occurrence of new AF, did not differ between treatment groups. By intention to treat, there were 139 cases of new AF in the atorvastatin group and 122 cases in the placebo group, corresponding to incidence rates of 1.32 and 1.14 cases per 100 patient-years observation (hazard ratio 1.15, 95% CI 0.90-1.46, P = .26). On-treatment analysis yielded similar findings, with incidence rates of 1.26 and 1.01 cases per 100 patient-years observation in the atorvastatin and placebo groups, respectively (hazard ratio 1.25, 95% CI 0.94-1.67, P = .12).

CONCLUSION

High-dose atorvastatin does not prevent development of AF in patients with prior stroke or transient ischemic attack.

Pathophysiological mechanisms of atrial fibrillation: a translational appraisal

Atrial fibrillation (AF) is an arrhythmia that can occur as the result of numerous different pathophysiological processes in the atria. Some aspects of the morphological and electrophysiological alterations promoting AF have been studied extensively in animal models. Atrial tachycardia or AF itself shortens atrial refractoriness and causes loss of atrial contractility. Aging, neurohumoral activation, and chronic atrial stretch due to structural heart disease activate a variety of signaling pathways leading to histological changes in the atria including myocyte hypertrophy, fibroblast proliferation, and complex alterations of the extracellular matrix including tissue fibrosis. These changes in electrical, contractile, and structural properties of the atria have been called "atrial remodeling." The resulting electrophysiological substrate is characterized by shortening of atrial refractoriness and reentrant wavelength or by local conduction heterogeneities caused by disruption of electrical interconnections between muscle bundles. Under these conditions, ectopic activity originating from the pulmonary veins or other sites is more likely to occur and to trigger longer episodes of AF. Many of these alterations also occur in patients with or at risk for AF, although the direct demonstration of these mechanisms is sometimes challenging. The diversity of etiological factors and electrophysiological mechanisms promoting AF in humans hampers the development of more effective therapy of AF. This review aims to give a translational overview on the biological basis of atrial remodeling and the proarrhythmic mechanisms involved in the fibrillation process. We pay attention to translation of pathophysiological insights gained from in vitro experiments and animal models to patients. Also, suggestions for future research objectives and therapeutical implications are discussed.

Update on the association of inflammation and atrial fibrillation

Atrial fibrillation (AF) is a common arrhythmia and is associated with significant morbidity and mortality. The pathogenesis of AF remains incompletely understood and management remains a difficult task. Over the past decade there has been accumulating evidence implicating inflammation in the pathogenesis of AF. Inflammation appears to play a significant role in the initiation and perpetuation of AF as well as the prothrombotic state associated with AF. Inflammatory biomarkers (C-reactive protein and interleukin-6) have been shown to be associated with the future development, recurrence and burden of AF, and the likelihood of successful cardioversion. Therapies directed at attenuating the inflammatory burden appear promising. Animal and clinical studies have evaluated statins, angiotensin-converting enzyme inhibitors/angiotensin-II receptor blockers, and corticosteroids for the treatment or prevention of AF. The purpose of this review is to provide current evidence on the relationship between inflammation and AF and potential therapies available to modulate the inflammatory state in AF.

Upstream effect for atrial fibrillation: still a dilemma?

Atrial fibrillation is the most common arrhythmia in clinical practice. Ion channel blocking agents are often characterized by limited long-term efficacy and several side effects. In addition, ablative invasive procedures are neither easily accessible nor always efficacious. The "upstream therapy," which includes angiotensin-converting enzyme inhibitors, aldosterone receptor antagonists, statins, glucocorticoids, and ω-3 poly-unsaturated fatty acids, targets arrhythmia substrate, influencing atrial structural and electrical remodeling that play an essential role in atrial fibrillation induction and maintenance. The mechanisms involved and the most important clinical evidence regarding the upstream therapy influence on atrial fibrillation are presented in this review. Some open questions are also proposed.

Advances in Antiarrhythmic Drug Therapy: New and Emerging Therapies

Despite major advances in the nonpharmacologic therapy for arrhythmias in the past decades, there is still a substantial role for antiarrhythmic drugs especially in the treatment of atrial fibrillation and ventricular tachycardia, the most effective of which is amiodarone. Dronedarone has been developed by modifying the amiodarone molecule, thus retaining its multichannel blocking action while still reducing its toxicity. New potassium channel blockers such as vernakalant are currently under development for the treatment of atrial fibrillation and flutter. So-called upstream therapies such as renin-angiotension system antagonists, statins, and n-3 polyunsaturated fatty acids offer promise for the treatment of antiarrhythmia. This article reviews dronedarone, which is already approved and available; antiarrhythmic agents that are the most advanced in development; and upstream therapy for atrial fibrillation.

Atrial fibrillation and inflammation

Atrial fibrillation (AF) is the most common clinical arrhythmia. Recent investigations have suggested that inflammation might have a role in the pathophysiology of AF. In this review, the association between inflammation and AF, and the effects of several agents that have anti-inflammatory actions, such as statins, polyunsaturated fatty acids, corticosteroids and angiotensin-converting enzyme inhibitors and angiotensin receptor blockers, have been investigated.

Lack of effect of statins on maintenance of normal sinus rhythm following electrical cardioversion of persistent atrial fibrillation

Randomised controlled trials evaluating the effect of statin use on maintenance of normal sinus rhythm (NSR) after electrical cardioversion (ECV) of persistent atrial fibrillation (AF) have demonstrated conflicting results. However, many of these trials were of relatively small size and thus underpowered to adequately evaluate this end-point. The aim of this study was to conduct a meta analysis evaluating the effect of statin use on maintenance of NSR after ECV of persistent AF. Randomised controlled trials evaluating the use of statins to maintain NSR after ECV of AF were identified through a systematic search including Medline (1950 through December 2009), the Cochrane CENTRAL Register (4th quarter, 2009) and a manual review of references without any language restrictions. Pooled estimates of effect are reported as relative risks (RRs) with accompanying 95% confidence intervals (CIs) using a random-effects model. Four trials (n = 424; range: 48-212) were identified and subject to meta analysis. Evaluated statins included atorvastatin 10 and 80 mg and pravastatin 40 mg/day. Over a mean of 2.1 months (range: 1-3 months) statins did not increase the likelihood of maintaining NSR following ECV (RR, 1.12; 95%CI, 0.85-1.46) compared with control. Current evidence does not suggest that statins are associated with an increased probability of maintaining NSR following ECV of persistent AF.

Adjuvant therapy for atrial fibrillation

Atrial fibrillation (AF) is the most common heart rhythm disorder, with increasing prevalence in the aging US population and affecting more than 2.3 million people. Current approaches for managing AF are rate- or rhythm-control strategies, both using anti-thrombotic therapy to prevent thromboembolism. While great advances have been made in understanding the pathophysiology of AF, few new strategies have shown promise in prevention or treatment of AF. Recent data suggest that non-antiarrhythmic medication may be useful in modifying the substrate that allows AF precipitation and perpetuation. This article reviews the data on the role of these agents in the prevention and management of AF as an adjunct to standard therapy.

Non-atheroprotective effects of statins: a systematic review

Since the introduction of HMG-CoA reductase inhibitors (statins) for lowering lipids, a large amount of data has been published demonstrating their potential benefits in conditions as varied as cancer, osteoporosis, and Alzheimer's dementia. We reviewed the published literature on MEDLINE from articles between 1950 and 2008 on the non-atheroprotective effects of statins and noted consistent benefits of statin use in improving outcomes of ventricular arrhythmias, sudden cardiac death, cardiac transplant rejection, chronic obstructive pulmonary disease, and sepsis. However, for these conditions, the level of evidence was inadequate to recommend statin use. The evidence for improving outcomes in atrial fibrillation, mortality in heart failure, contrast-induced nephropathy, cataract, age-related macular degeneration, sub-arachnoid hemorrhage, osteoporosis, dementia, and cancer incidence was conflicting and inconclusive. Furthermore, we found that most of the literature consists of small observational studies and their conclusions are often not corroborated by results from larger or randomized studies. Pending large, well designed, randomized trials, we conclude that there is no definite evidence for the use of statins in any condition besides hyperlipidemia and atherosclerosis.

Dose dependent effect of statins on postoperative atrial fibrillation after cardiac surgery among patients treated with beta blockers

Background

Previous studies on the effects of Statins in preventing atrial fibrillation (AF) after cardiac surgery have shown conflicting results. Whether statins prevent AF in patients treated with postoperative beta blockers and whether the statin-effect is dose related are unknown.

Methods

We retrospectively studied 1936 consecutive patients who underwent coronary artery bypass graft (CABG) (n = 1493) or valve surgery (n = 443) at the Minneapolis Veterans Affairs Medical Center. All patients were in sinus rhythm before the surgery. Postoperative beta blockers were administered routinely (92% within 24 hours postoperatively).

Results

Mean age was 66+10 years and 68% of the patients were taking Statins. Postoperative AF occurred in 588 (30%) patients and led to longer length of stay in the intensive care unit versus those without AF (5.1+7.6 days versus 2.5+2.3 days, p < 0.0001). Patients with a past history of AF had a 5 times higher risk of postoperative AF (odds ratio 5.1; 95% confidence interval 3.4 to 7.7; p < 0.0001). AF occurred in 31% of patients taking statins versus 29% of the others (p = 0.49). In multivariable analysis, statins were not associated with AF (odds ratio (OR) 0.93, 95% confidence interval (CI) 0.7 to 1.2; p = 0.59). However, in a subgroup analysis, the patients treated with Simvastatin >20 mg daily had a 36% reduction in the risk of postoperative AF (OR 0.64, 95% CI 0.43 to 0.6; p = 0.03) in comparison to those taking lower dosages.

Conclusion

Among cardiac surgery patients treated with postoperative beta blockers Statin treatment reduces the incidence of postoperative AF when used at higher dosages

Is there a role for statins in atrial fibrillation?

3-Hydroxy-3-methyl-glutaryl-CoA reductase inhibitors (statins) are some of the most commonly prescribed drugs in the world. While lipid modification remains the primary function of statins, there has been increasing interest in its potential pleiotropic effects, particularly as an anti-inflammatory agent in its role as an antiarrhythmic. Atrial fibrillation (AF) is the most common arrhythmia encountered in clinical practice and carries with it a significant burden in both morbidity and mortality. Treatment for AF currently involves either rate or rhythm control where both have demonstrable associated risks. Rate control necessitates anticoagulation, which can cause life-threatening bleeding, while rhythm control has a poor side-effect profile that may lead to greater mortality and may not completely eliminate the need for anticoagulation. Considering this pressing need for novel therapeutic interventions in AF, this long overdue systematic review explores the potential role of statins in the treatment and prevention of AF. Physicians, especially cardiologists, need to be aware of the host of currently available literature and, more importantly, need to be stimulated to generate discussion and formulate studies that will help debate the issues under the most erudite standards.

Upstream therapy of atrial fibrillation

Failure of current pharmacological therapy for atrial fibrillation in maintaining sinus rhythm may be due to structural atrial remodeling caused by inflammation and fibrosis. Upstream therapy that interferes in the structural remodeling process may be effective in maintaining sinus rhythm. This article reviews upstream therapy in atrial fibrillation. Various prospective and retrospective studies demonstrate that upstream therapy, consisting of angiotensin-converting enzyme inhibitors, angiotensin receptor blockers, statins, fish oils, glucocorticoids, or moderate physical activity, is associated with a reduced incidence of new-onset atrial fibrillation (i.e., primary prevention) and with a reduced recurrence of atrial fibrillation (i.e., secondary prevention). Larger clinical trials are required to further elucidate the position of upstream therapy in the primary and secondary prevention of atrial fibrillation.

Statins and prevention of atrial fibrillation in patients with heart failure

Statins are highly effective and widely used lipid-lowering agents in clinical practice, that also display a number of pleiotropic properties beyond cholesterol lowering. Several trials have demonstrated that they reduce cardiovascular morbidity and mortality in both primary and secondary prevention. Atrial fibrillation (AF) and heart failure (HF) represent 2 world-wide epidemics. Recent evidence suggests that statins may have beneficial effects on cardiovascular outcomes in patients with HF, and specifically in the prevention of AF. The anti-arrhythmic mechanisms of statins regarding AF prevention in HF patients are not fully understood but are possibly related to their pleiotropic effects including anti-inflammatory, antioxidant, atrial remodeling attenuation, ion channel stabilization, and autonomic nervous system regulation.

Pleiotropic effects of statins in atrial fibrillation patients: the evidence

Atrial fibrillation (AF) is the most common sustained arrhythmia in clinical practice. The understanding of the pathophysiology of AF has changed during the last several decades, and a significant role of inflammation and of the renin-angiotensin-aldosterone system has been postulated both experimentally and clinically. There is emerging evidence of an association between inflammation and AF, and mounting evidence links increased C-reactive protein levels not only to already existing AF but also to the risk of developing future AF. The beneficial effects of statins on AF have been reported in several studies. Several randomized clinical and large observational studies have shown similar result that show the beneficial effect of statins in AF. In clinical studies, statins were considered effective in preventing AF after electrical cardioversion, post-ablation, and after permanent pacemaker and implantable cardioverter defibrillator insertion. The antiarrhythmic mechanisms of statins regarding AF prevention in patients with heart failure are still not clear. Perioperative statin use has been associated with favorable postoperative outcome in both cardiovascular and noncardiovascular conditions. Despite a growing body of evidence that drugs with anti-inflammatory properties such as statins may prevent AF, the observed positive effects of statins on the burden of AF appeared to be independent of their cholesterol-reducing properties. However, further data from large-scale randomized trials are clearly needed.

Atrial Remodeling And Atrial Fibrillation: Mechanistic Interactions And Clinical Implications

Atrial fibrillation (AF) is the most common arrhythmia in clinical practice. The prevalence of AF increases dramatically with age and is seen in as high as 9% of individuals by the age of 80 years. In high-risk patients, the thromboembolic stroke risk can be as high as 9% per year and is associated with a 2-fold increase in mortality. Although the pathophysiological mechanism underlying the genesis of AF has been the focus of many studies, it remains only partially understood. Conventional theories focused on the presence of multiple re-entrant circuits originating in the atria that are asynchronous and conducted at various velocities through tissues with various refractory periods. Recently, rapidly firing atrial activity in the muscular sleeves at the pulmonary veins ostia or inside the pulmonary veins have been described as potential mechanism,. AF results from a complex interaction between various initiating triggers and development of abnormal atrial tissue substrate. The development of AF leads to structural and electrical changes in the atria, a process known as remodeling. To have effective surgical or catheter ablation of AF good understanding of the possible mechanism(s) is crucial.Once initiated, AF alters atrial electrical and structural properties that promote its maintenance and recurrence. The role of atrial remodeling (AR) in the development and maintenance of AF has been the subject of many animal and human studies over the past 10-15 years. This review will discuss the mechanisms of AR, the structural, electrophysiologic, and neurohormonal changes associated with AR and it is role in initiating and maintaining AF. We will also discuss briefly the role of inflammation in AR and AF initiation and maintenance, as well as, the possible therapeutic interventions to prevent AR, and hence AF, based on the current understanding of the interaction between AF and AR.

Efficacy of gemfibrozil in the primary prevention of atrial fibrillation in a large randomized controlled trial

BACKGROUND

Peroxisome proliferator-activated receptor alpha (PPARalpha) activators reduce inflammation and oxidative stress. Inflammation plays an important role in the initiation and maintenance of atrial fibrillation (AF). It has been suggested that PPARalpha activators may have antiarrhythmic properties, but no clinical data exist. The objective of this study was to investigate whether the PPARalpha activator gemfibrozil prevents or delays the development of AF in patients with coronary heart disease.

METHODS

We retrospectively analyzed the electrocardiograms (ECGs) performed in the Veterans Affairs High-Density Lipoprotein Cholesterol Intervention Trial, a multicenter, randomized, double-blinded, secondary prevention trial of gemfibrozil and matching placebo. The ECGs were performed annually or biannually and when clinically indicated. Participants who were in AF on baseline ECG were excluded from the present analysis. Relative risk for AF was calculated from Cox regression with death as a competing risk factor.

RESULTS

A total of 12,605 ECGs from 2,130 participants were interpreted (5.9 +/- 2.1 ECGs per participant, range 2-20). At baseline, the gemfibrozil (n = 1,070) and placebo (n = 1,060) groups were well matched. Mean age was 64.1 +/- 7.1 years. Over 4.4 +/- 1.5 years of follow-up, 123 (5.8%) participants developed new AF. There was no difference in AF incidence between the gemfibrozil and placebo groups (64/1,070 vs 59/1,060, respectively; P = .33). In Cox regression, the risk of AF was similar between the 2 study groups (hazard ratio 1.04, 95% CI 0.73-1.49, P = .82).

CONCLUSIONS

In this post hoc analysis of a multicenter, double-blinded, randomized controlled trial, the PPARalpha activator gemfibrozil did not reduce the 4-year incidence of AF among men with coronary heart disease.

Atrial fibrillation in heart failure: current treatment of patients with remodeled atria

Atrial fibrillation (AF) and chronic heart failure (CHF) can be caused by each other, and therefore constitute a vicious circle. The prevalence of both conditions is about 1% in industrialized countries and increases with age. Although mortality is increased in heart failure, the additional prognostic relevance of AF in these patients is less clear. AF in patients with CHF can worsen heart failure symptoms, cause complications (eg, stroke), and is difficult to treat. Thus, prevention of AF entirely is an important goal. This review summarizes recent data concerning prognostic relevance, treatment, and means of primary and secondary prevention of AF in patients with CHF.

Statin use is associated with lower risk of atrial fibrillation in women with coronary disease: the HERS trial

OBJECTIVE

To determine the efficacy of statin treatment in atrial fibrillation (AF) prevention in women.

DESIGN

Cohort study using data obtained in the Heart and Estrogen/Progestin Replacement Study (HERS).

SETTING

Secondary analysis of a multicentre, randomised controlled clinical trial.

PATIENTS

2673 Postmenopausal women with coronary disease.

MAIN OUTCOME MEASURES

AF prevalence at baseline and incident AF over a mean follow-up of 4.1 years.

RESULTS

88 Women with AF were identified: 29 at baseline and 59 during follow-up. Women with AF were significantly less likely to be taking a statin at study enrollment than those without AF (22% vs 37%, p = 0.003). Baseline statin use was associated with a 65% lower odds of having AF at baseline after controlling for age, race, history of myocardial infarction or revascularisation and history of heart failure (odds ratio 0.35, 95% confidence interval (CI) 0.13 to 0.93, p = 0.04). The risk of developing AF during the study among those free from AF at baseline, adjusted for the same covariates, was 55% less for those receiving statin treatment (hazard ratio 0.45, 95% CI 0.26 to 0.78, p = 0.004).

CONCLUSIONS

Statin treatment is associated with a lower prevalence and incidence of AF after adjustment for potential confounders in postmenopausal women with coronary disease.

Pathophysiology of concomitant atrial fibrillation and heart failure: implications for management

Atrial fibrillation (AF) and heart failure (HF) are two conditions regularly encountered in clinical practice. They share many common risk factors, and are often seen concurrently in an individual patient. Global aging of the population is likely to lead to an increase in the prevalence of both AF and HF alone, as well as in their combined state. The relationship between these two diseases is not simply coincidental; clinical and experimental data have defined multiple pathophysiological mechanisms to explain how either condition contributes to the de novo development of the other. The development of AF in the setting of HF, and vice versa, is associated with clinical deterioration and worsening prognosis, which indicates the need for an improved understanding of the clinical and pathological relationships between these conditions. Future research on pharmacologic therapies, such as antiarrhythmic medications, and nonpharmacologic strategies including atrioventricular nodal ablation and pulmonary vein isolation, will help to define the optimal therapeutic approach for concurrent AF and HF. This step is vital to improve both the outcomes of patients affected by these conditions and the cost-effectiveness of their care.

The impact of statin use on atrial fibrillation

The aim of the present systematic review is to present an overview of the evidence linking atrial fibrillation (AF), inflammation and oxidative stress, with emphasis on the potential of statins to decrease the incidence of different types of AF, including new-onset AF, after electrical cardioversion (EC) and after cardiac surgery. Observational and clinical trials have studied the impact of statin therapy on new-onset, post-EC or postoperative AF. Data from different observational trials have shown that treatment with statins significantly reduces the incidence of new-onset AF in the primary and secondary prevention. The data are insufficient to recommend the use of statins before EC. Finally, perioperative statin therapy may represent an important non-antiarrhythmic adjunctive therapeutic strategy for the prevention of postoperative AF.