Therapy with angiotensin-converting enzyme inhibitors, angiotensin II receptor blockers, and statins: no effect on ablation outcome after ablation of atrial fibrillation

Pathophysiology and clinical relevance of atrial myopathy

Atrial myopathy is a condition that consists of electrical, structural, contractile, and autonomic remodeling of the atria and is the substrate for development of atrial fibrillation, the most common arrhythmia. Pathophysiologic mechanisms driving atrial myopathy are inflammation, oxidative stress, atrial stretch, and neurohormonal signals, e.g., angiotensin-II and aldosterone. These mechanisms initiate the structural and functional remodeling of the atrial myocardium. Novel therapeutic strategies are being developed that target the pathophysiologic mechanisms of atrial myopathy. In this review, we will discuss the pathophysiology of atrial myopathy, as well as diagnostic and therapeutic strategies.

A Systematic Review and Meta-analysis of Renin-angiotensin System Inhibitors and Angiotensin Receptor Neprilysin Inhibitors in Preventing Recurrence After Atrial Fibrillation Ablation

ABSTRACT

To systematically evaluate the efficacy and safety of renin-angiotensin system inhibitors (RASIs) and angiotensin receptor neprilysin inhibitors in preventing the recurrence of atrial fibrillation after atrial fibrillation ablation, we have written this meta-analysis. We systematically searched randomized controlled trials or cohort studies on RASIs and angiotensin receptor neprilysin inhibitor-sacubitril/valsartan (SV) in preventing the recurrence of atrial fibrillation. Two researchers independently screened the literature, extracted the data, and assessed the risk of bias in the included studies. Afterward, the meta-analysis was performed using RevMan 5.3 software. This meta-analysis results showed that the recurrence rate of atrial fibrillation after ablation in subjects using RASIs was lower than that in subjects not using them [relative risk = 0.85, 95% confidence interval (CI) (0.72-0.99), P = 0.03]; the recurrence rate in subjects using SV was lower than that in subjects using RASIs [RR= 0.50, 95% CI (0.37-0.68), P < 0.00001]. These results show that both the use of RASIs and SV can prevent the recurrence of after atrial fibrillation ablation, among which the use of SV is more effective.

The Atrium in Atrial Fibrillation - A Clinical Review on How to Manage Atrial Fibrotic Substrates

Atrial fibrillation (AF) is the most common sustained arrhythmia in the population and is associated with a significant clinical and economic burden. Rigorous assessment of the presence and degree of an atrial arrhythmic substrate is essential for determining treatment options, predicting long-term success after catheter ablation, and as a substrate critical in the pathophysiology of atrial thrombogenesis. Catheter ablation of AF has developed into an essential rhythm-control strategy. Nowadays is one of the most common cardiac ablation procedures performed worldwide, with its success inversely related to the extent of atrial structural disease. Although atrial substrate evaluation remains complex, several diagnostic resources allow for a more comprehensive assessment and quantification of the extent of left atrial structural remodeling and the presence of atrial fibrosis. In this review, we summarize the current knowledge on the pathophysiology, etiology, and electrophysiological aspects of atrial substrates promoting the development of AF. We also describe the risk factors for its development and how to diagnose its presence using imaging, electrocardiograms, and electroanatomic voltage mapping. Finally, we discuss recent data regarding fibrosis biomarkers that could help diagnose atrial fibrotic substrates.

Prevention of Atrial Fibrillation After Atrial Flutter Ablation With Ramipril (from the PREFACE Study)

The clinical efficacy of the inhibitors of the renin-angiotensin-aldosterone system (RAAS) as an upstream therapy for atrial fibrillation (AF) prevention is controversial. No study has itemized so far the role of RAAS inhibitors in AF prevention after atrial flutter (AFL) ablation. This trial aims to investigate the effect of ramipril compared with placebo on AF occurrence in patients hospitalized for AFL ablation without structural heart disease. The Prevention of Atrial Fibrillation by Inhibition Conversion Enzyme (ICE) After Radiofrequency Ablation of Atrial Flutter (PREFACE) trial was a prospective, multicenter, randomized, double-blind, double-dummy trial depicting the AF occurrence during a 12-month follow-up as the primary end point. A total of 198 patients hospitalized for AFL ablation were enrolled in the trial and randomized to placebo or ramipril 5 mg/day. Patients were followed up during 1 year after AFL ablation using 1-week Holter electrocardiogram at 3, 6, 9, and 12 months. The intention-to-treat population encompassed 97 patients in the ramipril group and 101 patients in the placebo group. The primary end point, such as AF occurrence during the 1-year follow-up, was not different between the 2 groups (p = 0.96). Secondary end points, including the occurrence of supraventricular arrhythmia (p = 0.50), heart failure, stroke, and death, were not different between the 2 groups. Safety outcome parameters, including serious adverse events leading to treatment disruption (p = 0.10), hypotension, impairment of renal function, and elevated serum potassium level, also were not different between the 2 groups. In conclusion, RAAS inhibition using ramipril does not reduce AF occurrence in patients facing AFL ablation during the 1-year follow-up.

Update on the efficacy of statins in primary and secondary prevention of atrial fibrillation

Atrial fibrillation is the most common arrhythmia in adults and its prevalence is growing rapidly. It has been shown that AF is associated with increased risk of heart failure, ischemic and hemorrhagic stroke, and mortality. Hence, there is growing interest among researchers in seeking preventive and therapeutic interventions regarding AF. In recent decades, it has been suggested that statins may decrease the incidence of AF and may also decrease its recurrence after cardioversion and catheter ablation. These effects are thought to be mediated by different mechanisms such as modulating inflammation, altering the properties of transmembrane ion channels, interfering with activation of matrix metalloproteinases, and acting on endothelial function. In this article, we review and update current knowledge about the role of statins in primary and secondary prevention of AF in general and specific populations.

Update on the efficacy of statins in primary and secondary prevention of atrial fibrillation

Atrial fibrillation is the most common arrhythmia in adults and its prevalence is growing rapidly. It has been shown that AF is associated with increased risk of heart failure, ischemic and hemorrhagic stroke, and mortality. Hence, there is growing interest among researchers in seeking preventive and therapeutic interventions regarding AF. In recent decades, it has been suggested that statins may decrease the incidence of AF and may also decrease its recurrence after cardioversion and catheter ablation. These effects are thought to be mediated by different mechanisms such as modulating inflammation, altering the properties of transmembrane ion channels, interfering with activation of matrix metalloproteinases, and acting on endothelial function. In this article, we review and update current knowledge about the role of statins in primary and secondary prevention of AF in general and specific populations.

Renin-Angiotensin System Inhibitors for the Prevention of Atrial Fibrillation Recurrence After Ablation - A Meta-Analysis

BACKGROUND

Atrial fibrillation (AF) recurrence remains a tricky problem in patients undergoing ablation. This meta-analysis aimed to summarize the current literature to clarify whether renin-angiotensin system inhibitors (RASIs) prevent AF recurrence after ablation.Methods and Results:Relevant studies were searched on Pubmed and EMBASE through December 2019. Pooled relative risk (RR) of AF recurrence was calculated. Subgroup analyses according to study design, race, and follow-up duration were further performed. A total of 15 studies examining 4,300 patients were included, with 3 randomized controlled trials and 12 cohort studies. Overall analysis showed that RASIs significantly reduced AF recurrence after ablation (RR=0.83; 95% confidence interval (CI) 0.70-0.98, P=0.028; I²=68.9%). Subgroup analysis further indicated that positive results were found in randomized controlled trials (RR=0.51, 95% CI 0.37-0.70, P<0.001; I²=4%), studies conducted in Asia (RR=0.59, 95% CI 0.46-0.76, P<0.001; I²=30.7%), and studies with follow-up duration ≥1 year (RR=0.82, 95% CI 0.70-0.95, P=0.01; I²=59.1%); negative results were found in cohort studies, studies conducted in Europe or the USA, and studies with follow-up duration <1 year.

CONCLUSIONS

RASIs can potentially prevent AF recurrence after ablation under selected conditions. However, more studies are required to confirm this finding due to the variation in current evidence.

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.

Effect of Postablation Statin Treatment on Arrhythmia Recurrence in Patients With Paroxysmal Atrial Fibrillation

BACKGROUND

Statins have been proposed as a means to prevent postablation atrial fibrillation (AF) recurrences, mainly on the basis of their pleiotropic effects. The objective of this subanalysis of a prospectively randomized controlled study population of patients undergoing radiofrequency ablation for paroxysmal AF was to test the hypothesis that statin treatment is associated with longer time to recurrence.

METHODS AND RESULTS

This is a subanalysis over an extended follow-up period of a prospective randomized study (ClinicalTrials.gov Identifier NCT01791699). Among 291 patients, 2 propensity score-matched subgroups of patients who received or did not receive statins after pulmonary vein isolation were created. In the unmatched cohort, there was no difference in the rate of recurrence between statin-treated and not treated patients, with a 1-year recurrence estimate of 19% and 23%, respectively (Gehan statistic 0.59, P = 0.443). In the propensity-matched cohort (N = 166, 83 per group), recurrence-free survival did not differ significantly between groups (839 days, 95% confidence interval 755-922 days, in the no statin group vs. 904 days, 95% confidence interval 826-983 in the statin group; P = 0.301). The 1-year recurrence rate estimate was 30% in the no statin group versus 27% in the statin group (Gehan statistic 0.56, P = 0.455).

CONCLUSION

Statin treatment does not seem to affect AF recurrence in following radiofrequency ablation for paroxysmal AF, over a follow-up time of about 2.5 years.

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.

Telmisartan reduces atrial arrhythmia susceptibility through the regulation of RAS-ERK and PI3K-Akt-eNOS pathways in spontaneously hypertensive rats

Telmisartan is an angiotensin II receptor blocker that displays unique PPAR-γ modulating activity. PPAR-γ agonists have been shown to decrease susceptibility to atrial fibrillation through their antioxidant and antiapoptotic effects. The aim of this study was to determine whether telmisartan would have a greater effect on susceptibility to atrial arrhythmia in a hypertensive rat model than valsartan, which is a traditional angiotensin II receptor blocker. In this study, spontaneously hypertensive rats were treated with 10 mg·(kg body mass)(-1)·d(-1) telmisartan (TEL group), 10 mg·(kg body mass)(-1)·d(-1) valsartan (VAL group), or vehicle (saline; SHR group) for 4 weeks. Age-matched Wistar-Kyoto rats (WKY) were used as normotensive controls. After 4 weeks of treatment, we performed echocardiographic assessment, electrophysiological analysis, histological evaluation, and Western blot analysis. Telmisartan decreased systolic blood pressure to a similar extent as valsartan. Relative to the WKY controls, atrial arrhythmia susceptibility was significantly increased in the SHR group, and was significantly decreased by both telmisartan and valsartan, albeit to a greater extent with telmisartan. Arrhythmogenic atrial remodeling, including enlargement of the left atrium, myocyte hypertrophy, interstitial fibrosis, and myocyte apoptosis, was observed in the SHR group, and was accompanied by activated RAS-ERK signaling and suppressed PI3K-Akt-eNOS signaling. The results suggest that telmisartan reduced susceptibility to atrial arrhythmia to a greater extent than valsartan, ameliorated atrial remodeling, and reversed imbalances in the RAS-ERK and PI3K-Akt-eNOS pathways.

The Role Of Renin Angiotensin System In Atrial Fibrillation

Atrial fibrillation (AF) is the most prevalent arrhythmia and its incidence is on the rise. AF causes significant morbidity and mortality leading to rising AF-related health care costs. There is experimental and clinical evidence from animal and human studies that suggests a role for the renin angiotensin system (RAS) in the etiopathogenesis of AF. This review appraises the current understanding of RAS antagonism, using angiotensin converting enzyme inhibitors (ACE-I), angiotensin receptor blockers (ARB) and aldosterone antagonists (AA), for prevention of AF. RAS antagonism has proven to be effective for primary and secondary prevention of AF in subjects with heart failure and left ventricular (LV) dysfunction.However, most of the evidence for the protective effect of RAS antagonism is from clinical trials that had AF as a secondary outcome or from unspecified post-hoc analyses. The evidence for prevention in subjects without heart failure and with normal LV function is not as clear. RAS antagonism, in the absence of concomitant antiarrhythmic therapy, was not shown to reduce post cardioversion AF recurrences. RAS antagonism in subjects undergoing catheter ablation has also been ineffective in preventing AF recurrences.

Antiarrhythmic therapy following ablation of atrial fibrillation

Antiarrhythmic drugs (AADs) are often used after ablation for atrial fibrillation (AF); the drugs employed vary, but most common are the drugs that were unsuccessful prior to ablation since it seems that the efficacy of AADs might substantially increase after catheter ablation of AF. AADs reduce early recurrences of atrial tachyarrhythmias after AF catheter ablation, whereas they did not prevent arrhythmia recurrences occurring later. Several upstream therapies (angiotensin-converting enzyme inhibitors, angiotensin receptor blockers, statins, corticosteroids and colchicine) have been tested with conflicting results. To date, there is no sufficient evidence to support the use of any upstream therapy after AF catheter ablation. Larger registries and controlled clinical trials in well-defined patient groups and with well-defined outcome parameters are required to further elucidate the role of AADs after AF ablation.

Renin Angiotenin Blocker Pre-treatment and Recurrence After Pulmonary Vein Isolation in Patients with Paroxysmal and Persistent Atrial Fibrillation

Introduction: Pulmonary venous isolation has emerged as an effective method for preventing atrial fibrillation (AF) recurrence. Yet, recurrence is common. Angiotensin-receptor-blockers (ARBs) and angiotensin-converting-enzyme-inhibitors (ACEI) are effective in reducing the extent of myocardial remodeling and fibrosis. Our aim was to study whether pretreatment with ARBs and ACEI was effective in decreasing recurrence after pulmonary vein isolation for patients with AF. Methods: Three hundred and twelve consecutive patients who underwent ablation from 12/2006 until 7/2010 were followed for at least one year. All patients underwent MRI before ablation to assess atrial fibrosis. Data include demographic characteristics, comorbidities, AF type and information regarding treatment with ACEI or ARBs. Results: Most patients were men (62%), mean age was 64. Hypertension (HTN) was present in 60%. Their mean ejection fraction was 60%. There were 104 patients (33.3%) treated with ACEI, and 13.5 % were treated with ARBs prior to ablation. Ninety seven patients (31.1%) had AF recurrence. AF type was a significant predictor for recurrence (recurrence with paroxysmal, persistent and long-standing persistent: 23.75, 37.3 and 60%, respectively, p=0.005). The most important factor predicting recurrence was increased pre-ablation atrial fibrosis (p<0.0001). Recurrence was more frequent in patients treated with ACEI (40.4% vs 26.4% untreated patients, p=0.012). In the ARB treated group, 38.1% vs 30.0% untreated experienced recurrence (p=0.3). After multivariable adjustment for demographics, risk factors and atrial fibrosis, treatment with ACEI was associated with increased rate of recurrence in patients with persistent AF (hazard ratio: 2.6, p=0.003). There was no significant relation between ACEI pretreatment and recurrence in patients with paroxysmal AF (HR- 0.83, p=0.7), or between ARB pre-treatment and recurrence in patients with paroxysmal as well as persistent AF (p=0.2 and 0.53, respectively). Conclusions: Pretreatment with ACEI or ARBs is not associated with reduced recurrence rate in patients with paroxysmal or persistent AF undergoing ablation.

Diabetes, Obesity and Atrial Fibrillation: Epidemiology, Mechanisms and Interventions

Body mass index (BMI) is a powerful predictor of death, type 2 diabetes (T2DM) and cardiovascular (CV) morbidity and mortality. Over the last few decades, we have witnessed a global rise in adult obesity of epidemic proportions. Similarly, there has been a parallel increase in the incidence of atrial fibrillation (AF), itself a significant cause of cardiovascular morbidity and mortality. This may be partly attributable to advances in the treatment of coronary heart disease (CHD) and heart failure (HF) improving life expectancy, however, epidemiological studies have demonstrated an independent association between obesity, diabetes and AF, suggesting possible common pathophysiological mechanisms and risk factors. Indeed, cardiac remodeling, haemodynamic alterations, autonomic dysfunction, and diastolic dysfunction have been reported in obese and diabetic cohorts. Moreover, diabetic cardiomyopathy is characterized by an adverse structural and functional cardiac phenotype, which may predispose to the development of AF. In this review, we discuss the pathophysiological and mechanistic relationships between obesity, diabetes and AF, and some of the challenges posed in the management of this high-risk group of individuals.

During ablation for atrial fibrillation, is simultaneous renal artery ablation appropriate?

Over the past few decades, the mainstay of hypertension management has been pharmacological therapy; however, there is now a growing body of evidence that drug-resistant hypertension can be managed effectively by renal artery ablation. Several studies have documented the feasibility and safety of this treatment, although data regarding long-term outcomes are still emerging. Atrial fibrillation (AF) and hypertension commonly coexist, and recent work has demonstrated improved outcomes from catheter ablation of AF with concomitant renal artery denervation at little extra cost in terms of time and resource. The aim of this review is to explore the link between hypertension and AF, the synergistic effect of renal artery ablation on AF ablation, explain how this may work and address unanswered questions.

Impact of aldosterone antagonists on the substrate for atrial fibrillation: aldosterone promotes oxidative stress and atrial structural/electrical remodeling

Atrial fibrillation (AF), the most common cardiac arrhythmia, is an electrocardiographic description of a condition with multiple and complex underlying mechanisms. Oxidative stress is an important driver of structural remodeling that creates a substrate for AF. Oxidant radicals may promote increase of atrial oxidative damage, electrical and structural remodeling, and atrial inflammation. AF and other cardiovascular morbidities activate angiotensin (Ang-II)-dependent and independent cascades. A key component of the renin-angiotensin-aldosterone system (RAAS) is the mineralocorticoid aldosterone. Recent studies provide evidence of myocardial aldosterone synthesis. Aldosterone promotes cardiac oxidative stress, inflammation and structural/electrical remodeling via multiple mechanisms. In HF patients, aldosterone production is enhanced. In patients and in experimental HF and AF models, aldosterone receptor antagonists have favorable influences on cardiac remodeling and oxidative stress. Therapeutic approaches that seek to reduce AF burden by modulating the aldosterone system are likely beneficial but underutilized.

Obesity, diabetes and atrial fibrillation; epidemiology, mechanisms and interventions

The last few decades have witnessed a global rise in adult obesity of epidemic proportions. The potential impact of this is emphasized when one considers that body mass index (BMI) is a powerful predictor of death, type 2 diabetes (T2DM) and cardiovascular (CV) morbidity and mortality [1, 2]. Similarly we have witnessed a parallel rise in the incidence of atrial fibrillation (AF), the commonest sustained cardiac arrhythmia, which is also a significant cause of cardiovascular morbidity and mortality. Part of this increase is attributable to advances in the treatment of coronary heart disease (CHD) and heart failure (HF) improving life expectancy and consequently the prevalence of AF. However, epidemiological studies have demonstrated an independent association between obesity and AF, possibly reflecting common pathophysiology and risk factors for both conditions. Indeed, weight gain and obesity are associated with structural and functional changes of the cardiovascular system including left atrial and ventricular remodeling, haemodynamic alterations, autonomic dysfunction, and diastolic dysfunction. Moreover, diabetic cardiomyopathy is characterized by an adverse structural and functional cardiac phenotype which may predispose to the development of AF [3]. In this review, we discuss the pathophysiological and mechanistic relationships between obesity, diabetes and AF, and the challenges posed in the management of this high-risk group of individuals.

The role of the renin-angiotensin system blocking in the management of atrial fibrillation

OBJECTIVE

To review current available evidence for the role of renin-angiotensin system blockade in the management of atrial fibrillation.

METHOD

We conducted a PubMed and Medline literature search (January 1980 through July 2011) to identify all clinical trials published in English concerning the use of angiotensin converting enzyme inhibitors or angiotensin II receptor blockers for primary and secondary prevention of atrial fibrillation. We also discussed renin-angiotensin system and its effects on cellular electrophysiology.

CONCLUSION

The evidence from the current studies discussed does not provide a firm definitive indication for the use of angiotensin converting enzyme inhibitors or angiotensin II receptor blockers in the primary or secondary prevention of atrial fibrillation. Nevertheless, modest benefits were observed in patients with left ventricular dysfunction. In view of the possible benefits and the low incidence of side-effects with angiotensin converting enzyme inhibitors and angiotensin II receptor blockers, they can be given to patients with recurrent AF, specifically those with hypertension, heart failure and diabetes mellitus.

Renin-Angiotensin System and AtrialFibrillation:Understanding the Connection

Atrial fibrillation (AF) arises as a result of a complex interaction of triggers, perpetuators and the substrate. The recurrence of AF may be partially related to a biologic phenomenon known as remodeling, in which the electrical, mechanical, and structural properties of the atrial tissue and cardiac cells are progressively altered,creating a more favorable substrate. Atrial remodeling is in part a consequence of arrhythmia itself. Therefore,to prevent and to treat AF, much attention has been directed to upstream therapies to alter the arrhythmia substrate and to reduce atrial remodeling. The renin-angiotensin-aldosterone system (RAAS) plays a keyrole in these strategies. In this review we analyze the experimental and clinical evidence regarding the efficacy of RAAS inhibitors in AF treatment. In the primary prevention of AF, meta-analyses have shown that risk of new-onset AF in patients with congestive heart failure and left ventricular dysfunction is reduced by RAAS inhibitors, whereas in hypertensive and post-myocardial infarction patients, the results are less evident. In the secondary prevention of AF, some large, prospective, randomized, placebo-controlled studieswith angiotensin II-receptor blockers returned negative results. Unfortunately, the approach of using RAASinhibitors as antiarrhythmic drugs to prevent both new-onset and recurrent AF is in decline because negativetrial results are accumulating, with the exception of the results in patients with congestive heart failure.

Markers of oxidative stress after ablation of atrial fibrillation are associated with inflammation, delivered radiofrequency energy and early recurrence of atrial fibrillation

BACKGROUND

The role of oxidative stress after radiofrequency ablation of atrial fibrillation (AF) has not yet been well characterized. We sought to evaluate the time course of biomarkers of oxidative stress and inflammation after AF ablation and their association with clinical variables.

METHODS

Thirty consecutive patients (57.9 ± 1.7 years, 63% males) with paroxysmal AF underwent pulmonary vein isolation and ablation of complex fractionated atrial electrograms. Biomarkers were determined in blood samples before ablation and 6 h, 1, 2, 7, 30, 90 and 180 days post-ablation.

RESULTS

The pro-oxidant enzyme myeloperoxidase and oxidized low-density lipoprotein reflecting oxidant damage of lipoproteins increased 2.9 ± 0.2-fold and 1.2 ± 0.1-fold, respectively, and were significantly up-regulated until day 2 post-ablation. The anti-oxidant enzyme copper/zinc superoxide dismutase did not change significantly. Inflammatory markers significantly increased (high-sensitivity C-reactive protein (hs-CRP): 41 ± 8-fold; interleukin-6: 4.4 ± 0.7-fold) for 7 and 2 days, respectively. The increase of myeloperoxidase and hs-CRP was interrelated and both predicted early recurrence of AF within the first post-ablation week (both p < 0.05). The increase of both markers was associated with the amount of delivered radiofrequency energy (p < 0.05). The up-regulation of hs-CRP correlated with troponin T (p = 0.008), while myeloperoxidase and troponin T were borderline associated (p = 0.054). However, the oxidative and inflammatory responses did not predict long-term ablation outcome (p > 0.05).

CONCLUSIONS

Markers of oxidative stress showed a significant up-regulation during the first 2 days after AF ablation. Their up-regulation was linked to inflammation, delivered radiofrequency energy, and early recurrence of AF, but did not predict long-term ablation outcome.

IntravenousCorticosteroid Use Is Associated With Reduced Early Recurrence of Atrial Fibrillation Immediately Following Radiofrequency Catheter Ablation

Background: Early recurrence of atrial fibrillation (ERAF) occurs in up to 40% of patients after radiofrequency catheter ablation for atrial fibrillation (RFCA), increasing hospital stay, need for anti-arrhythmic medications (AADs) and cardioversion, and, possibly, the risk of future AF. It has been postulated that inflammation plays a key role in developing ERAF. Short term postoperative use of corticosteroids to reduce ERAF post-RFCA has not been vigorously studied. Methods: This was a case-control study of consecutive patients undergoing RFCA for the management of AF at a single-institution. RFCA was performed by a single operator from October 2005 through July 2009. Patients receiving intravenous corticosteroids immediately following the ablation and for 48 hours (6 doses) constituted the treatment group. Controls received no intravenous corticosteroids during their hospitalization. All other management strategies were similar between the 2 groups, including the administration of AADs post- operatively. All patients had continuous electrocardiographic monitoring throughout their hospitalization. Multivariable logistic regression analysis was used to determine the impact of intravenous corticosteroids on ERAF defined as any AF>10 minutes during hospitalization. Results: A total of 68 patients undergoing RFCA for the management of AF were included in this analysis. The overall ERAF rate, irrespective of intravenous corticosteroid use, was 23.5%. The administration of intravenous corticosteroids (n=37; mean±SD dexamethasone mean dose 11.9±4.6 mg/day; range 4-16 mg/day) was associated with an 82% reduction in patients' odds of ERAF (adjusted odds ratio; 0.18, 95% confidence interval [CI] 0.04 to 0.78) compared with those who did not receive corticosteroids (n=31). A dose-response effect was also observed, with a 17% reduction in ERAF odds for each dexamethasone mg-equivalent administered (adjusted odds ratio; 0.83, 95%CI 0.73 to 0.96). Conclusions: The use of intravenous corticosteroids was associated with a dose-dependent reduction in the odds of developing ERAF after RFCA for the management of AF.

PPAR-γ activator pioglitazone prevents age-related atrial fibrillation susceptibility by improving antioxidant capacity and reducing apoptosis in a rat model

INTRODUCTION

The in vivo role of peroxisome proliferator-activated receptor (PPAR)-γ, an essential transcriptional mediator of lipid and glucose metabolism, in atrial fibrillation (AF) remains to be fully elucidated. We investigated the effects of pioglitazone, a PPAR-γ activator, in an in vivo AF rat model.

METHODS AND RESULTS

We studied 3 groups of Wistar rats: young group, 3-month-old rats treated with vehicle; aged group, 9-month-old rats treated with vehicle; and aged+Pio group, 9-month-old rats treated with pioglitazone. After 4-week treatment, AF duration induced by 30-second burst pacing, gene and protein expressions, and atrial structural changes were compared between the 3 groups. Atrial oxidant reducing activity was measured by electron spin resonance method. AF duration was markedly prolonged in the aged group but significantly shortened in the aged+Pio group. Age-induced decrease in free radical reducing activity was reversed by pioglitazone. Gene and protein expression levels of antioxidant molecules Sod2 (MnSOD) and Hspa1a (heat shock 70 protein) were significantly enhanced, and p22(phox) and gp91(phox), two NADPH oxidase subunits, were significantly decreased in aged+Pio rats. Pioglitazone treatment significantly increased phosphorylated (p-) Akt but significantly reduced p-ERK1/2 and p-JNK. Pioglitazone significantly restored p-Bad and reduced cleaved caspase-3 and -9, indicating that pioglitazone prevented age-related enhancement of apoptotic signaling. Microscopic analysis revealed suppression of age-related histological changes (interstitial fibrosis and apoptosis) by pioglitazone.

CONCLUSIONS

Pioglitazone inhibited age-related arrhythmogenic atrial remodeling and AF perpetuation by improving antioxidant capacity and inhibiting the mitochondrial apoptotic signaling pathway. PPAR-γ activators could become a novel upstream therapy for age-related AF.

Atorvastatin for prevention of atrial fibrillation recurrence following pulmonary vein isolation: a double-blind, placebo-controlled, randomized trial

BACKGROUND

It is known that statins are effective in preventing atrial fibrillation (AF) in patients undergoing cardiac surgery.

OBJECTIVE

The purpose of this study was to evaluate the efficacy of statins in preventing AF recurrence following left atrial ablation.

METHODS

One hundred twenty-five patients who had no statin indication undergoing catheter ablation due to drug-refractory paroxysmal (n = 90) or persistent (n = 35) AF were randomized in a prospective, double-blind, placebo-controlled trial to receive 80 mg atorvastatin (n = 62) or placebo (n = 63) for 3 months. The primary endpoint was freedom from symptomatic AF at 3 months. Secondary endpoints included freedom from any atrial arrhythmia recurrence irrespective of symptoms, quality of life (QoL), and reduction in C-reactive protein (CRP).

RESULTS

At 3 months, 95% of patients in the atorvastatin group were free of symptomatic AF compared with 93.5% in the placebo group (P = .75). Similarly, 85% of patients treated in the atorvastatin group remained free of any recurrent atrial arrhythmia vs 88% of patients in the placebo group (P = .37). Mean CRP levels decreased in the atorvastatin group (mean change -0.75 ± 3, P = .02) and increased in the placebo group (mean change 2.1 ± 19.9, P = .48). Mean QoL score improved significantly in both groups (mean change 13.14 ± 18.2 in the atorvastatin group and 11.10 ± 17.7 in the placebo group, P = .53).

CONCLUSION

In patients with no standard indication for statin therapy, treatment with atorvastatin 80 mg/day following AF ablation does not decrease the risk of AF recurrence in the first 3 months and should not be routinely administered to prevent periprocedural arrhythmias.

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.

Therapy with renin-angiotensin system blockers after pulmonary vein isolation in patients with atrial fibrillation: who is a responder?

AIMS

The data on anti-arrhythmic effect of renin-angiotensin-aldesteron system blockers (RASB) in patients with atrial fibrillation (AF) are controversially discussed. The goal of this analysis was to identify cohort of patients with AF and hypertension, who may have benefit from RASB therapy after pulmonary vein isolation (PVI).

METHODS

A total of 284 patients with AF and hypertension (paroxysmal AF [PAF]= 218, male = 185, age = 61 years, left ventricular ejection fraction = 60%, coronary artery disease = 42) considered for PVI were included. The patients with PAF were stratified according to time spent in AF (AF burden) within 3 months prior to admission (</> 500 hours). Further patients were divided into two groups: (1) low-burden AF; (2) high-burden AF (PAF and persistent AF). In 195 patients, RASB therapy was administered. A 7-day continuous Holter electrocardiogram was performed after discharge, every 3 months thereafter and by symptoms.

RESULTS

Preventive effect of RASB was revealed in whole group (112 out of 195 [57%] vs 36 out of 89 [40%]; P = 0.025) and was more pronounced in patients with low-burden AF (79 out of 112 [71%] receiving RASB vs 27 out of 55 [49%] being on other drugs; P = 0.013). However, efficiency of RASB failed in patients with high-burden AF (33 out of 83 on RASB [40%] vs nine out of 34 on other drugs [27%]; P = 0.328).

CONCLUSIONS

Our data suggest that RASB appears to protect against AF recurrences after PVI in patients with low-burden paroxysmal AF. These results should be tested in a prospective study.

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.

Focus on renin-angiotensin system modulation and atrial fibrillation control after GISSI AF results

Atrial fibrillation is the most frequently encountered arrhythmia in clinical practice. Given that atrial fibrillation is steadily increasing and that the medium to long-term efficacy of antiarrhythmic drugs has proved poor, it is essential to seek new therapies to prevent its onset and to effectively control recurrences. The study of nonantiarrhythmic drugs that act on the atrial remodeling that constitutes the substrate of the arrhythmia is a new and very interesting field of research. In this regard, several molecules that interact with the renin-angiotensin system at the level of the enzymatic or receptor cascade have been investigated in the past 10 years; some results have been very promising, whereas others have been extremely disappointing. In particular, the publication in 2008 of the results of GISSI AF, a rigorously designed Italian prospective study conducted on a large number of patients, revealed no statistically significant differences between the active drug and a placebo in preventing arrhythmia recurrences. In this study, we reassess the rationale behind the use of this class of drugs for 'antiarrhythmic' purposes, re-examine the most significant results reported in the clinical literature since 1999 and discuss the results of the GISSI AF study in this light.

Inhibition of the renin-angiotensin system for prevention of atrial fibrillation

Atrial fibrillation (AF) is a source of considerable morbidity and mortality. There has been compelling evidence supporting the role of renin-angiotensin system (RAS) in the genesis and perpetuation of AF through atrial remodeling, and experimental studies have validated the utilization of RAS inhibition for AF prevention. This article reviews clinical trials on the use of angiotensin-converting enzyme inhibitors (ACEIs) and angiotensin receptor blockers (ARBs) for the prevention of AF. Results have been variable, depending on the clinical background of treated patients. ACEIs and ARBs appear beneficial for primary prevention of AF in patients with heart failure, whereas they are not equally effective in hypertensive patients with normal left ventricular function. Furthermore, the use of ACEIs or ARBs for secondary prevention of AF has been found beneficial only after electrical cardioversion. Additional data are needed to establish the potential clinical role of renin-angiotensin inhibition for prevention of 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.

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.

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.