Effect of statins on preventing recurrence of atrial fibrillation after electrical cardioversion

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.

Use of statins and recurrence of atrial fibrillation after catheter ablation or electrical cardioversion

Statins have important pleiotropic effects and have been shown to reduce vascular inflammation. Some evidence suggests that statins may have a role in the primary prevention of atrial fibrillation (AF), whereas little is know on the role of statins in patients with existing AF. We performed a meta-analysis of the literature to assess the effect of statins on the recurrence of AF after electrical cardioversion or ablation. MEDLINE and EMBASE databases were searched up to January 2010. Relative risks (RR) and 95% confidence intervals (CIs) were then calculated and pooled using a random-effects model. Statistical heterogeneity was evaluated through the use of I2 statistics. Sixteen studies were included in our systematic review. Statins did not reduce the risk of AF recurrence after ablation (four studies including 750 patients; RR, 1.04; 95% CI, 0.85–1.28, p=0.71; I2 = 34%). Conversely, the use of statins was associated with a significantly reduced risk of AF recurrence after electrical cardioversion (12 studies including 1790 patients; RR, 0.78; 95% CI, 0.67–0.90, p=0.0003; I2 = 34%). This reduction was not statistically significant when the analysis was restricted to randomised controlled trials (RCTs) only (five studies, 458 patients, RR, 0.76; 95% CI, 0.48–1.20). In conclusion, statins may lower the risk of AF recurrence after electrical cardioversion, but not ablation. However, this finding should be considered with caution, and larger RCTs are warranted to confirm our preliminary results.

The efficacy and tolerability of commonly used agents to prevent recurrence of atrial fibrillation after successful cardioversion

A number of therapeutic strategies exist for the restoration and maintenance of sinus rhythm in patients presenting with atrial fibrillation. The acute success rate with electrical cardioversion is high. However, many patients relapse into atrial fibrillation. A major challenge faced by those who care for patients with atrial fibrillation is the long-term maintenance of sinus rhythm whilst avoiding treatment-related adverse effects. This review examines the efficacy and tolerability of conventional anti-arrhythmic drugs for the secondary prevention of atrial fibrillation in the post-cardioversion period.

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 effects of statin on atrial fibrillation: a meta-analysis of published data from randomized controlled trials

BACKGROUND

Some clinical and experimental studies have shown the use of statins could protect against AF, but there are not adequate data at present.

OBJECTIVES

We performed a meta-analysis of randomized trials with statins on the endpoint of incidence of AF to estimate the impact of statin use on AF development.

METHODS

We searched PUBMED, EMBASE and the Cochrane controlled Trials Register (Cochrane Library Issue 4, 2010) up to November 2010 to identify studies covering the use of statins on atrial fibrillation.

RESULTS

In published data from nine short term trials (1044 patients, 421 AF), the effect of statins was significantly associated with a decreased risk of recurrence of AF (OR 0.43, 95% CI 0.25 to 0.73, P = 0.002). The result of OR was higher when studies with Jadad score ≤3 were excluded (OR 0.32, 95% CI 0.18 to 0.54, P ≤ 0.0001). Among four long term trials (12,442 patients, 618 AF), the effect of statins was associated with a decreased risk of recurrence of AF (OR 0.81, 95% CI 0.68 to 0.97, P = 0.02). In three long term trials of more intensive versus standard statin (9130 patients, 188 AF), there was no evidence of a reduction in the risk of AF (OR 1.05, 95% CI 0.79 to 1.40, P= 0.74).

CONCLUSION

Our meta-analysis suggests that the use of statins may be associated with preventing AF in short term trials and long term trials, but in the long term trials of more intensive versus standard statin, there was no evidence of a reduction in the risk of AF. However, we still need large-scale randomized double blind statin trials with AF occurrence as the main endpoint in order to finally confirm the benefits of statin in AF patients.

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

Fundamental research into molecular mechanisms of atrial fibrillation (AF) and improved understanding of processes involved in the initiation and maintenance of AF have transformed the traditional approach to its management by targeting only the electrical aspects, usually with antiarrhythmic drugs and, recently, by ablation. The antiarrhythmic potential of upstream therapies, such as angiotensin-converting enzyme inhibitors, angiotensin receptor blockers (ARBs), statins, and n-3 (ω-3) polyunsaturated fatty acids, extends beyond the benefit of treating underlying heart disease to modifying the atrial substrate and intervening in specific mechanisms of AF. The key target is structural remodelling of the atria, particularly inflammation and fibrosis, although there is evidence to suggest the direct involvement at the ion channel level. Positive clinical reports supported by robust experimental data have suggested that upstream therapies can be valuable strategies for primary prevention of AF in selected patients and have resulted in several class IIA recommendations in the new European guidelines on AF. However, these results have not been consistently replicated in the secondary prevention setting, and several recent randomized controlled studies failed to demonstrate any effect of upstream therapies on AF burden or on major cardiovascular outcomes. Part II of the review summarizes the evidence base for the use of upstream therapies for secondary prevention of AF.

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.

Atorvastatin given prior to electrical cardioversion does not affect the recurrence of atrial fibrillation in patients with persistent atrial fibrillation who are on antiarrhythmic therapy

OBJECTIVE

In this study, our aim was to evaluate the effect of a higher dose of atorvastatin on the recurrence rate of atrial fibrillation (AF) after electrical cardioversion (EC) in addition to antiarrhythmic therapy.

SUBJECTS AND METHODS

48 patients with persistent AF were included in this study. The patients were randomized to an atorvastatin 40-mg treatment group and a control group. Atorvastatin was started 3 weeks before EC and was continued for 2 months after EC. EC was performed using biphasic shocks after 3 weeks of treatment with the orally administered anticoagulant warfarin. Lipid and inflammatory parameters (high-sensitivity C-reactive protein, white blood cell count and fibrinogen level) were evaluated at the baseline and before EC. The endpoint of this study was electrocardiographically confirmed recurrence of AF of >10 min.

RESULTS

There were no significant differences in baseline characteristics and lipid and inflammatory marker levels between the treatment and control groups. Total cholesterol and low-density lipoprotein levels were significantly decreased in patients taking atorvastatin for 2 months compared with baseline values (174 ± 31 vs. 129 ± 25 mg/dl, p = 0.001, and 112 ± 23 vs. 62 ± 20 mg/dl, p = 0.001, respectively), while no significant change occurred in control patients (168 ± 26 vs. 182 ± 29 mg/dl, p = 0.07, and 99 ± 18 vs. 108 ± 26 mg/dl, p = 0.1, respectively). At the end of the 2-month follow-up period, 9 patients (20.5%) experienced AF recurrence, and there was no significant difference in AF recurrence rate between the treatment and control groups (26 vs. 13%; p = 0.2).

CONCLUSION

Atorvastatin therapy prior to EC does not prevent the recurrence of arrhythmia in patients with persistent AF who are receiving antiarrhythmic therapy.

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.

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.

Non-antiarrhythmic drugs to prevent atrial fibrillation

Atrial fibrillation (AF) is the most frequent arrhythmia found in clinical practice. The majority of patients with AF are still candidates for antiarrhythmic drug treatment, not only for acute reversion to sinus rhythm but also for long-term treatment to prevent recurrences of AF. Currently available antiarrhythmic drugs, however, are unable to provide complete efficacy in all patients, and present problematic risks of proarrhythmia. The progressively increasing prevalence of AF supports the need to develop improved therapeutic approaches for the clinical management of arrhythmia. Accordingly, new treatment techniques aimed at suppressing the origin of the arrhythmogenic foci have been developed in the last decade. However, ablative treatments are only available for selected patients. Because of these factors, and also because primary prevention of AF should be our goal, the introduction of non-antiarrhythmic agents that could prevent both new-onset AF and recurrences of AF may eventually improve patient outcomes and reduce the incidence of this epidemic disease. The potential clinical value of these non-antiarrhythmic options is currently under active investigation. There is now clinical and experimental evidence that many drugs may have beneficial effects in preventing AF through several possible mechanisms. Non-antiarrhythmic drugs, such as ACE inhibitors and angiotensin receptor blockers, HMG-CoA reductase inhibitors (statins), corticosteroids, and N-3 polyunsaturated fatty acids may have a positive effect in patients with AF or in preventing AF in patients at risk.

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.

Primary and secondary prevention of atrial fibrillation with statins and polyunsaturated fatty acids: review of evidence and clinical relevance

Atrial fibrillation (AF) is an increasingly common arrhythmia that now stands at epidemic proportion, with more than 2.3 million people affected in the USA and over 4.5 million people affected in Western Europe. AF is an expression of underlying heart disease and is increasingly associated with hypertension, congestive heart failure, and ischemic heart disease. It is also a progressive disease secondary to continuous structural remodeling of the atria, which relates to AF itself, to changes associated with aging and to progression of the underlying heart disease. Traditionally, AF has been addressed only after it has already presented with pharmacological and nonpharmacological therapies designed for rhythm or rate control (secondary prevention). Although secondary prevention is the most feasible approach at present, the concept of primary prevention of AF with therapies aimed at preventing the development of substrate and correcting the risk factors for AF has emerged as a strategy, which is likely to produce a larger effect in the general population. Recent experiments provided new insights into AF pathophysiology, which generated background for new mechanism-based therapies. Agents targeting inflammation, oxidative injury, atrial myocyte metabolism, extracellular matrix remodeling, and fibrosis have theoretical advantages as novel therapeutic strategies. In this respect, drugs that are not traditionally antiarrhythmic such as angiotensin-converting enzyme inhibitors, angiotensin-receptor blockers, aldosterone antagonists, statins, and omega-3 polyunsaturated fatty acids have shown an antiarrhythmic potential in addition to any treatment effect on the underlying disease. These agents are thought to have an advantage of targeting both the occurrence and progression of the substrate for AF, thus, providing primary and secondary prevention of the arrhythmia. Although first experimental and hypothesis-generating small clinical studies or retrospective analyses have been encouraging, several larger, properly designed, prospective trials have not confirmed earlier observations. This review provides a contemporary evidence-based insight into the possible preventative and reverse remodeling role of statins and polyunsaturated fatty acids in AF.

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.