Pharmacological prevention of atrial tachycardia induced atrial remodeling as a potential therapeutic strategy

Proton pump inhibitors as also inhibitors of atrial fibrillation

Proton pump inhibitors (PPIs) are widely used for the treatment of acid-related upper digestive diseases, including gastric and duodenal ulcer and gastroesophageal reflux disease (GERD). Remarkably, several small clinical trials have shown that these drugs also reduce the symptoms and frequency of atrial fibrillation (AF) episodes in patients treated for comorbid acid reflux. Although the mechanism remains unclear, the effect might pinpoint a connection between GERD and AF. To this end, it is known that both oxidants and inflammation affect initiation and maintenance of AF, and PPIs may reduce symptoms and frequency of AF episodes through their antioxidant and anti-inflammatory effects. This review focuses on the anti-AF effects of PPIs beyond their inhibition of gastric acid production.

Ionic mechanisms of pacemaker activity in spontaneously contracting atrial HL-1 cells

Although normally absent, spontaneous pacemaker activity can develop in human atrium to promote tachyarrhythmias. HL-1 cells are immortalized atrial cardiomyocytes that contract spontaneously in culture, providing a model system of atrial cell automaticity. Using electrophysiologic recordings and selective pharmacologic blockers, we investigated the ionic basis of automaticity in atrial HL-1 cells. Both the sarcoplasmic reticulum Ca release channel inhibitor ryanodine and the sarcoplasmic reticulum Ca ATPase inhibitor thapsigargin slowed automaticity, supporting a role for intracellular Ca release in pacemaker activity. Additional experiments were performed to examine the effects of ionic currents activating in the voltage range of diastolic depolarization. Inhibition of the hyperpolarization-activated pacemaker current, If, by ivabradine significantly suppressed diastolic depolarization, with modest slowing of automaticity. Block of inward Na currents also reduced automaticity, whereas inhibition of T- and L-type Ca currents caused milder effects to slow beat rate. The major outward current in HL-1 cells is the rapidly activating delayed rectifier, IKr. Inhibition of IKr using dofetilide caused marked prolongation of action potential duration and thus spontaneous cycle length. These results demonstrate a mutual role for both intracellular Ca release and sarcolemmal ionic currents in controlling automaticity in atrial HL-1 cells. Given that similar internal and membrane-based mechanisms also play a role in sinoatrial nodal cell pacemaker activity, our findings provide evidence for generalized conservation of pacemaker mechanisms among different types of cardiomyocytes.

Inducibility of atrial fibrillation depends not on inflammation but on atrial structural remodeling in rat experimental autoimmune myocarditis

INTRODUCTION

There is increasing evidence to support a link between inflammation and atrial fibrillation (AF). However, the role of inflammation on new-onset AF is still to be elucidated.

METHODS

Rats underwent induction of experimental autoimmune myocarditis (EAM). Atrial structural change was evaluated by echocardiography and histological analysis. Electrophysiological data and the in vivo atrial response to burst atrial pacing were evaluated in the acute (2 weeks after EAM induction) and chronic phases (8 weeks after induction). In addition, atrial pacing after 2, 4, and 6 h after lipopolysaccharide (LPS) infusion, when the expression of gap junctions was modified, were challenged with young healthy rats.

RESULTS

AF was induced in 11 of 15 chronic phase EAM rats but not in either acute phase EAM rats or LPS infusion rats (P<.01). Echocardiography showed dilatation of both atrium and ventricle and a decrease in the ejection fraction in the chronic phase. Histology revealed severe inflammatory lesions only in the acute phase. Interstitial atrial fibrosis as well as the area of atrial myocyte increased in the chronic phase but not in the acute phase.

CONCLUSIONS

AF could be induced in the chronic phase of myocarditis rats, but not in the acute phase of myocarditis rats or in rats with LPS infusion. Acute inflammation per se did not increase the occurrence of AF induction. Atrial structural remodeling caused by inflammation and hemodynamic effects is necessary to induce AF.

Optimizing the management of atrial fibrillation: focus on current guidelines and the impact of new agents on future recommendations

Atrial fibrillation (AF) is the most common sustained cardiac arrhythmia encountered in everyday clinical practice. It affects ~2.3 million individuals in the United States, and the prevalence is expected to increase ~2.5-fold over the next 40 years. Atrial fibrillation accounts for more than 2 million hospitalizations each year and contributes to nearly 67 000 deaths. Our understanding of the pathophysiology of AF has increased dramatically over the past few decades. Recent treatment guidelines have heightened our awareness of the challenges involved in the treatment of AF and provided useful recommendations for its diagnosis and management. Because AF is usually associated with multiple comorbid conditions, greater emphasis must be placed on individualizing treatment. This review focuses on current treatment guidelines for patients with AF, assessing the benefits and shortcomings of current pharmacologic options and discussing new agents and trials that may provide better opportunities to improve and individualize patient management.

Role of TGF-beta on cardiac structural and electrical remodeling

The type β transforming growth factors (TGF-βs) are involved in a number of human diseases, including heart failure and myocardial arrhythmias. In fact, during the last 20 years numerous studies have demonstrated that TGF-β affects the architecture of the heart under both normal and pathological conditions. Moreover, TGF-β signaling is currently under investigation, with the aim of discovering potential therapeutic roles in human disease. In contrast, only few studies have investigated whether TGF-β affects electrophysiological properties of the heart. This fact is surprising since electrical remodeling represents an important substrate for cardiac disease. This review discusses the potential role of TGF-β on cardiac excitation-contraction (EC) coupling, action potentials, and ion channels. We also discuss the effects of TGF-β on cardiac development and disease from structural and electrophysiological points of view.

Oxidative stress: a possible pathogenesis of atrial fibrillation

Atrial fibrillation (AF) is the most commonly sustained arrhythmia in clinical practice. Despite the extensive studies, the pathophysiology of AF, however, remains incompletely understood. Studies have demonstrated that oxidative stress may be involved in cardiac structural and electrical remodeling. More recently, a growing body of evidence suggests that oxidative stress is associated with the development of AF. The evidence for the hypotheses included that: (1) histological studies have demonstrated oxidative damage in both AF patients and animal models of AF; (2) oxidative stress markers are increased in AF patients, and are associated with the presence of AF; (3) drugs that have antioxidant properties show beneficial effects on AF development. Although the studies suggest the association between oxidative stress and AF, the exact pathogenesis of oxidative stress in AF development remains elusive and requires further investigation. Specifically, the causality between oxidative stress and AF; the levels of the oxidative stress in various types of AFs and their role in the pathogenesis of AF; the effects of strategies to reduce oxidative stress on atrial structural and electrical remodeling, and their exact role in the development of AF. Oxidative stress may provide a scientific basis for further research on the underlying mechanisms of AF and may target for pharmacological interruption of AF.

Inhibition of the renin-angiotensin system: effects on tachycardia-induced early electrical remodelling in rabbit atrium

Introduction. Tachycardia-induced atrial remodelling (as an equivalent to atrial fibrillation) can be influenced by the renin-angiotensin system. Effects of a seven-day enalapril pre-treatment (EPT, 0.16 mg/kg body weight subcutaneously every 24 h) on ionic currents underlying tachycardia-induced early electrical remodelling after 24 h rapid atrial pacing (RAP, 600 beats/min) in rabbit atrium were studied.

Materials and methods. Animals were divided into four groups (n=4 each): control; paced only; enalapril only; and enalapril and paced, respectively. Using patch-clamp technique in whole-cell mode, current densities were measured in isolated atrial myocytes. Results. EPT nearly doubled L-type calcium current (ICa,L, −7.7±0.6 pA/pF [control] vs. f −12.3±1.2 pA/pF [enalapril only]). RAP reduced ICa,L to −3.6±0.7 pA/pF (paced only). Also after EPT, RAP led to a significant downregulation of ICa,L by 39% (−7.5±1.3 pA/pF [paced and enalapril]). RAP decreased transient outward potassium current (Ito, −45%, 51.5±3.9 pA/pF [control] vs. 28.5±4.5 pA/pF [paced only]). EPT did not alter Ito (44.2±8.1 pA/pF [enalapril only]). However, RAP did not affect Ito in enalapril-treated animals and averaged 50.4±9.8 pA/pF (paced and enalapril).

Conclusions. In summary, EPT has several effects on ion channels in rabbit atrium: 1) EPT increases ICa,L current density, but cannot prevent its downregulation due to RAP; 2) EPT has no influence on Ito current density, but can prevent its downregulation due to RAP. Although changes of single ion channels must be interpreted in context of the complex atrial electrophysiology as a whole, our results provide a possible explanation of the in vivo observation that angiotensin-converting enzyme inhibition is mainly beneficial on the early electrical remodelling due to the atrial fibrillation-equivalent RAP.

Hyperthermia treatment prevents angiotensin II-mediated atrial fibrosis and fibrillation via induction of heat-shock protein 72

We tested the hypothesis that atrial fibrosis and atrial fibrillation (AF) evoked by angiotensin II (AII) could be prevented by the induction of heat-shock protein 72 (HSP72) by hyperthermia (HT). In cultured atrial fibroblasts isolated from male Sprague-Dawley rats, HT (42 degrees C) was applied for 30 min. AII (100 nmol/L) was added to the medium 8 h later. HT induced the expression of HSP72, which was associated with the attenuation of AII-induced extracellular signal-regulated kinase (ERK1/ERK2) phosphorylation, alpha-smooth muscle actin (alpha-SMA) expression, transforming growth factor-beta(1) secretion, collagen synthesis, and expression of collagen type I and tissue inhibitor of metalloproteinases-1. A small interfering RNA targeting HSP72 abolished these anti-fibrotic effects of HT. In male Sprague-Dawley rats in vivo, an osmotic mini-pump was subcutaneously implanted for continuous infusion of AII (400 ng/kg/min). Whole-body HT (43 degrees C, 20 min) was applied 24 h before and 7, 14, and 21 days after the start of the AII infusion. Repeated HT led to the induction of HSP72 expression, which resulted in an attenuation of AII-induced left atrial fibrosis. In an electrophysiological study using isolated perfused heart, continuous AII caused slowing of interatrial conduction without affecting atrial refractoriness. In AII-treated hearts, extrastimuli from the right atrial appendage resulted in a high incidence of repetitive atrial responses, which were suppressed by treatment with HT. Our results suggest that HT treatment is effective in suppressing AII-mediated atrial fibrosis and AF via induction of HSP72 at least in parts, and is thus expected to be a novel strategy for prevention of AF.

The role of oxidative stress in the pathogenesis and perpetuation of atrial fibrillation

Atrial fibrillation (AF) is the most common arrhythmia encountered in clinical practice representing a major health hazard. Owing to relative inefficacy and side effects of classic antiarrhythmic drugs, current interest has shifted to treatments that target AF substrate. Accumulating evidence suggests that there is a link between oxidative processes and AF. In atrial myocardium during AF, there is substantial oxidative damage that may contribute to atrial remodeling. Several pathophysiological changes that possibly associated with increased oxidative stress in AF have been proposed. These include changes in gene transcriptional profiles and mitochondrial DNA, increased activity of enzymes such as NAD(P)H oxidase and xanthine oxidase, inflammatory processes, activation of the renin-angiotensin system and others. Moreover, oxidative stress is involved in the pathophysiology of several predisposing factors and cardiovascular disorders that correspondingly associated with AF. Preliminary studies using dietary antioxidants such as vitamin C have shown promising results. More evidence has been obtained from studies examining agents with pleiotropic effects, including antioxidant, such as inhibitors of the renin-angiotensin system, statins, corticosteroids and carvedilol. Further investigations are needed in order to elucidate the impact of oxidative stress on atrial remodeling. The clarification of these processes in the setting of AF may lead to the development of novel therapeutic strategies.

Transforming growth factor-β1 decreases cardiac muscle L-type Ca2+ current and charge movement by acting on the Cav1.2 mRNA

Transforming growth factors-β (TGF-βs) are essential to the structural remodeling seen in cardiac disease and development; however, little is known about potential electrophysiological effects. We hypothesized that chronic exposure (6–48 h) of primary cultured neonatal rat cardiomyocytes to the type 1 TGF-β (TGF-β1, 5 ng/ml) may affect voltage-dependent Ca2+ channels. Thus we investigated T- ( ICaT) and L-type ( ICaL) Ca2+ currents, as well as dihydropyridine-sensitive charge movement using the whole cell patch-clamp technique and quantified CaV1.2 mRNA levels by real-time PCR assay. In ventricular myocytes, TGF-β1 did not exert significant electrophysiological effects. However, in atrial myocytes, TGF-β1 reduced both ICaL and charge movement (55% at 24–48 h) without significantly altering ICaT, cell membrane capacitance, or channel kinetics (voltage dependence of activation and inactivation, as well as the activation and inactivation rates). Reductions of ICaL and charge movement were explained by concomitant effects on the maximal values of L-channels conductance ( Gmax) and charge movement (Qmax). Thus TGF-β1 selectively reduces the number of functional L-channels on the surface of the plasma membrane in atrial but not ventricular myocytes. The TGF-β1-induced ICaL reduction was unaffected by supplementing intracellular recording solutions with okadaic acid (2 μM) or cAMP (100 μM), two compounds that promote L-channel phosphorylation. This suggests that the decreased number of functional L-channels cannot be explained by a possible regulation in the L-channels phosphorylation state. Instead, we found that TGF-β1 decreases the expression levels of atrial CaV1.2 mRNA (70%). Thus TGF-β1 downregulates atrial L-channel expression and may be therefore contributing to the in vivo cardiac electrical remodeling.

Nonantiarrhythmic drug therapy for atrial fibrillation

Recent studies have begun to elucidate the molecular mechanisms that promote the generation and progressive nature of atrial fibrillation. Evidence from both experimental and clinical investigations has implicated an important role for the renin-angiotensin-aldosterone system, inflammation, and oxidative stress, with data that suggest a potential beneficial effect for angiotensin-converting enzyme inhibitors, angiotensin receptor blockers, aldosterone receptor antagonists, antiinflammatory agents, 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitors (statins), and omega-3 polyunsaturated fatty acids. In addition, compounds that increase gap junctional conductance or that block 5-hydroxytryptamine-4 receptors have also shown promise in the experimental setting. Large-scale, prospective clinical trials will clarify the utility of these new therapeutic approaches to prevent atrial fibrillation in specific clinical settings.

Induction of heat shock response protects the heart against atrial fibrillation

There is evidence suggesting that heat shock proteins (HSPs) may protect against clinical atrial fibrillation (AF). We evaluated the effect of HSP induction in an in vitro atrial cell line (HL-1) model of tachycardia remodeling and in tachypaced isolated canine atrial cardiomyocytes. We also evaluated the effect of HSP induction on in vivo AF promotion by atrial tachycardia-induced remodeling in dogs. Tachypacing (3 Hz) significantly and progressively reduced Ca(2+) transients and cell shortening of HL-1 myocytes over 4 hours. These reductions were prevented by HSP-inducing pretreatments: mild heat shock, geranylgeranylacetone (GGA), and transfection with human HSP27 or the phosphorylation-mimicking HSP27-DDD. However, treatment with HSP70 or the phosphorylation-deficient mutant HSP27-AAA failed to alter tachycardia-induced Ca(2+) transient and cell-shortening reductions, and downregulation (short interfering RNA) of HSP27 prevented GGA-mediated protection. Tachypacing (3 Hz) for 24 hours in vitro significantly reduced L-type Ca(2+) current and action potential duration in canine atrial cardiomyocytes; these effects were prevented when tachypacing was performed in cells exposed to GGA. In vivo treatment with GGA increased HSP expression and suppressed refractoriness abbreviation and AF promotion in dogs subjected to 1-week atrial tachycardia-induced remodeling. In conclusion, our findings indicate that (1) HSP induction protects against atrial tachycardia-induced remodeling, (2) the protective effect in HL-1 myocytes requires HSP27 induction and phosphorylation, and (3) the orally administered HSP inducer GGA protects against AF in a clinically relevant animal model. These findings advance our understanding of the biochemical determinants of AF and suggest the possibility that HSP induction may be an interesting novel approach to preventing clinical AF.

Inflammation: a possible pathogenic link to atrial fibrillation

Atrial fibrillation (AF) is the most common sustained dysrhythmia in clinical practice. Despite the extensive studies, the pathophysiological mechanisms in AF, however, remain unclear. More recently, the data has been suggested that inflammatory process has been associated with development of AF. The evidence for the hypotheses included that: (1) Histological studies have demonstrated inflammatory infiltrates in AF patients and in animal models of AF; (2) inflammatory markers are increased in AF patients and is associated with successful cardioversion. And also, Inflammatory markers are not only associated with the presence of AF but also independently predicted increased risk for the development of future AF; (3) treatment with anti-inflammatory agents is associated with a decreased recurrence of AF. Although the studies suggest the existence of an association between inflammation and AF, many aspects remain elusive and require further investigation. Specifically, whether inflammation is an initiator or a perpetuator of AF; the effects of anti-inflammatory drugs on atrial remodeling and their exact role in the recurrence and perpetuation of AF. Inflammation may provide a potential target for pharmacological interruption of AF and may favorably affect atrial remodeling leading to important clinical benefits.

Physiology of Local Renin-Angiotensin Systems

Since the first identification of renin by Tigerstedt and Bergmann in 1898, the renin-angiotensin system (RAS) has been extensively studied. The current view of the system is characterized by an increased complexity, as evidenced by the discovery of new functional components and pathways of the RAS. In recent years, the pathophysiological implications of the system have been the main focus of attention, and inhibitors of the RAS such as angiotensin-converting enzyme (ACE) inhibitors and angiotensin (ANG) II receptor blockers have become important clinical tools in the treatment of cardiovascular and renal diseases such as hypertension, heart failure, and diabetic nephropathy. Nevertheless, the tissue RAS also plays an important role in mediating diverse physiological functions. These focus not only on the classical actions of ANG on the cardiovascular system, namely, the maintenance of cardiovascular homeostasis, but also on other functions. Recently, the research efforts studying these noncardiovascular effects of the RAS have intensified, and a large body of data are now available to support the existence of numerous organ-based RAS exerting diverse physiological effects. ANG II has direct effects at the cellular level and can influence, for example, cell growth and differentiation, but also may play a role as a mediator of apoptosis. These universal paracrine and autocrine actions may be important in many organ systems and can mediate important physiological stimuli. Transgenic overexpression and knock-out strategies of RAS genes in animals have also shown a central functional role of the RAS in prenatal development. Taken together, these findings may become increasingly important in the study of organ physiology but also for a fresh look at the implications of these findings for organ pathophysiology.

Left Atrial Size

Left atrial (LA) enlargement has been proposed as a barometer of diastolic burden and a predictor of common cardiovascular outcomes such as atrial fibrillation, stroke, congestive heart failure, and cardiovascular death. It has been shown that advancing age alone does not independently contribute to LA enlargement, and the impact of gender on LA volume can largely be accounted for by the differences in body surface area between men and women. Therefore, enlargement of the left atrium reflects remodeling associated with pathophysiologic processes. In this review, we discuss the normal size and phasic function of the left atrium. Further, we outline the clinically important aspects and pitfalls of evaluating LA size, and the methods for assessing LA function using echocardiography. Finally, we review the determinants of LA size and remodeling, and we describe the evidence regarding the prognostic value of LA size. The use of LA volume for risk stratification is an evolving science. More data are required with respect to the natural history of LA remodeling in disease, the degree of LA modifiability with therapy, and whether regression of LA size translates into improved cardiovascular outcomes.

Selection of drugs in pursuit of rate control strategy

Atrial fibrillation is the most common sustained arrhythmia. Based on multiple large randomized trials, rate control therapy has been shown to be safe and effective and is gaining greater acceptance as a frontline alternative to drugs to maintain sinus rhythm. Adequate rate control can be achieved by atrioventricular nodal blocking agents both in the acute and chronic settings. In refractory patients, other methods such as atrioventricular node ablation can be used to control rate.

Chronic heart rate reduction remodels ion channel transcripts in the mouse sinoatrial node but not in the ventricle

We investigated the effects of chronic and moderate heart rate (HR) reduction on ion channel expression in the mouse sinoatrial node (SAN) and ventricle. Ten-week-old male C57BL/6 mice were treated twice daily with either vehicle or ivabradine at 5 mg/kg given orally during 3 wk. The effects of HR reduction on cardiac electrical activity were investigated in anesthetized mice with serial ECGs and in freely moving mice with telemetric recordings. With the use of high-throughput real-time RT-PCR, the expression of 68 ion channel subunits was evaluated in the SAN and ventricle at the end of the treatment period. In conscious mice, ivabradine induced a mean 16% HR reduction over a 24-h period that was sustained over the 3-wk administration. Other ECG parameters were not modified. Two-way hierarchical clustering analysis of gene expression revealed a separation of ventricles from SANs but no discrimination between treated and untreated ventricles, indicating that HR reduction per se induced limited remodeling in this tissue. In contrast, SAN samples clustered in two groups depending on the treatment. In the SAN from ivabradine-treated mice, the expression of nine ion channel subunits, including Navbeta1 (-25%), Cav3.1 (-29%), Kir6.1 (-28%), Kvbeta2 (-41%), and Kvbeta3 (-30%), was significantly decreased. Eight genes were significantly upregulated, including K+ channel alpha-subunits (Kv1.1, +30%; Kir2.1, +29%; Kir3.1, +41%), hyperpolarization-activated cation channels (HCN2, +24%; HCN4, +52%), and connexin 43 (+26%). We conclude that reducing HR induces a complex remodeling of ion channel expression in the SAN but has little impact on ion channel transcripts in the ventricle.

Mechanisms of Atrial Fibrillation: Lessons From Animal Models

Studies in animal models have provided extremely important insights about atrial fibrillation (AF). The classic mechanisms that still form the framework for our understanding of AF (focal activity, single-circuit or "mother wave" reentry, and multiple circuit reentry) were established based on animal studies almost 100 years ago. The past 10 years have witnessed a tremendous acceleration of animal work in this area, including the development of a range of AF models in clinically relevant pathological substrates (eg, atrial tachycardia remodeling, congestive heart failure, pericarditis, ischemic heart disease, mitral valve disease, volume overload states, respiratory failure) and the establishment of an increasing number of genetically defined transgenic mouse models. This article reviews the contribution of animal models to our knowledge about AF mechanisms and to clinical management, dealing with such issues as the theory of reentry; the specific applications of various animal models and their contribution to our understanding of electrophysiologic, ionic, and molecular mechanisms; the role of the autonomic nervous system and regional factors; and the development of novel therapeutic approaches. The complementary nature of animal research and clinical investigation is emphasized and the clinical relevance of findings in experimental models is highlighted.

Oral vitamin C administration reduces early recurrence rates after electrical cardioversion of persistent atrial fibrillation and attenuates associated inflammation

BACKGROUND

Inflammation and oxidative stress have been recently implicated in the pathophysiology of atrial fibrillation (AF). The aim of this study was to examine the potential benefit of vitamin C on the early recurrence rates and on inflammatory indices after successful cardioversion of persistent AF, as well as to investigate the time course of changes in these indices post-cardioversion.

METHODS

We prospectively studied 44 consecutive patients after successful electrical cardioversion of persistent AF. All patients received standard treatment and were randomised in one to one fashion to either oral vitamin C administration or no additional therapy. We followed-up the patients for 7 days performing successive measurements of white blood cell (WBC) count, C-reactive protein (CRP), fibrinogen, and ferritin levels.

RESULTS

One week after successful cardioversion, AF recurred in 4.5% of patients in the vitamin C group and in 36.3% of patients in the control group (p=0.024). Compared to baseline values, inflammatory indices decreased after cardioversion in patients receiving vitamin C but did not change significantly in the control group. A significant variance was found in the serial measurements of WBC counts (F=5.86, p=0.001) and of fibrinogen levels (F=4.10, p=0.0084) in the two groups. In the vitamin C group CRP levels were lower on the seventh day (p<0.05). CRP and fibrinogen levels were higher in patients who relapsed into AF compared to patients who maintained sinus rhythm (F=2.77, p=0.044 and F=3.51, p=0.017, respectively).

CONCLUSIONS

These findings suggest that vitamin C reduces the early recurrence rates after cardioversion of persistent AF and attenuates the associated low-level inflammation. These effects indicate that therapeutic approaches targeting at inflammation and oxidative stress may exert favourable effects on atrial electrical remodeling.

Comparative effects of carvedilol and amiodarone on conversion and recurrence rates of persistent atrial fibrillation

Pretreatment with antiarrhythmic agents could improve cardioversion and recurrence rates in patients with persistent atrial fibrillation. In a prospective controlled trial, 145 patients were randomly assigned to treatment with carvedilol, amiodarone, or placebo for 4 weeks before electrical cardioversion. Although the 2 drugs had similar effects on cardioversion rates, amiodarone was superior in terms of sinus rhythm maintenance after conversion.

Atrial Fibrillation in Heart Failure:

AF in Heart Failure. Atrial fibrillation and congestive heart failure are commonly occurring cardiac disorders that often exist concomitantly. The prognostic significance of the presence or absence of atrial fibrillation, as an independent risk factor, in patients with heart failure remains controversial. Antiarrhythmic drugs with good hemodynamic profiles and neutral effects on survival are preferred treatments for converting atrial fibrillation and maintaining sinus rhythm. Other standard therapies for congestive heart failure, such as angiotensin-converting enzyme inhibitors, angiotensin receptor blockers, and beta-blockers also have a role in the treatment of these coexisting disease states. The article presents an overview of atrial fibrillation in patients with heart failure and reviews the prevalence, prognostic significance, and efficacy of various antiarrhythmic agents for the conversion and maintenance of sinus rhythm.