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PubMed2006

The impact of suppressing the renin-angiotensin system on atrial fibrillation.

Atrial fibrillation is very common in the United States. After a search of Medline, EMBASE, and CINAHL, 4 trials evaluating inhibitors of the renin-angiotensin system were identified for prevention of new-onset atrial fibrillation, facilitation of electrical cardioversion of atrial fibrillation, and prevention of atrial fibrillation recurrence after electrical cardioversion. A meta-analysis was performed using a random-effects model. Use of an angiotensin-converting enzyme (ACE) inhibitor or angiotensin-receptor blocker (ARB) was associated with a reduction in new-onset atrial fibrillation (OR [95% CI] = 0.51 [0.36-0.72]), a lower failure rate of electrical cardioversion of atrial fibrillation (0.47 [0.24-0.92]), and a lower rate of recurrence of atrial fibrillation after electrical cardioversion (0.39 [0.20-0.75]). With the exception of the new-onset atrial fibrillation analysis, these findings were not associated with statistical heterogeneity. These hypothesis-generating data suggest that inhibitors of the renin-angiotensin system may provide benefit across the spectrum of atrial fibrillation.

Angiotensin II Type 1 Receptor Blockers↗

PubMed2005

Quality of life in atrial fibrillation: the Atrial Fibrillation Follow-up Investigation of Rhythm Management (AFFIRM) study.

OBJECTIVE: The objective of this prespecified substudy of the AFFIRM study, in which no differences in survival or event rates were found in patients with atrial fibrillation (AF) randomized to either rate control or rhythm control, was to test the null hypothesis that quality of life (QoL) is equal with rate- versus rhythm-control treatment strategies in AF. METHODS: Fifty-six (25%) of AFFIRM sites were randomly selected to recruit AFFIRM patients for the QoL substudy. Instruments used in the QoL assessment were (1) Perceived Health; (2) the Cantril Ladder of Life; (3) the Short Form 36 survey; (4) the QoL Index; and (5) the Symptom Checklist: Frequency and Severity. Data were collected at baseline, 2 months, 12 months, and annually; data are reported through 4 years of follow-up. RESULTS: Baseline characteristics of the AFFIRM QoL patients (n = 716) were generally similar to those of the rest of AFFIRM patients. Quality-of-life scores were similar in rate- and rhythm-control assignment groups at all time points. Quality-of-life scores were similar whether the actual rhythm was sinus or AF. Scores increased from baseline to subsequent time points similarly for both groups; these improvements were not additive over time. CONCLUSIONS: Quality of life was comparable between rate- and rhythm-control treatment strategies. In addition, QoL was similar with sinus rhythm versus AF. Attempts to improve QoL by restoring sinus rhythm will usually be unsuccessful.

Aged↗

PubMed2005

Clinical factors that influence response to treatment strategies in atrial fibrillation: the Atrial Fibrillation Follow-up Investigation of Rhythm Management (AFFIRM) study.

BACKGROUND: The AFFIRM Study was a randomized multicenter comparison of 2 treatment strategies, rate-control versus rhythm-control, in high-risk patients with atrial fibrillation (AF). The primary outcome of the trial showed no overall difference in survival between strategies. However, there may be important patient subgroups for which there are identifiable differences in outcome with 1 of the 2 strategies. METHODS AND RESULTS: Subgroups that were prespecified for analysis from the main AFFIRM Study were age, sex, coronary artery disease (CAD), hypertension, congestive heart failure (CHF), left ventricular ejection fraction (LVEF), rhythm at randomization, first episode of AF, and duration of the qualifying episode of AF. Baseline characteristics were analyzed for each subgroup. Adjusted hazard ratios for each subgroup and for each stratum were generated using Cox models, and these models were used to determine whether treatment strategy affected overall survival differentially by subgroup. Adjusted survival was worse for patients > or =65 years and for patients with a history of CHF, CAD, or an abnormal LVEF. In the adjusted analyses, the effect of treatment strategy was similar within all of the prespecified subgroups. When each subgroup stratum was analyzed separately, patients > or =65 years and patients without a history of CHF had significantly better outcome with rate-control therapy (each P < .01). CONCLUSIONS: Overall, treatment effect for rate control versus rhythm control was the same within each subgroup. However, certain selected patient categories may have better survival with one particular strategy for management of AF.

Age Factors↗

PubMed1995

Comparison of CT in patients with cerebral ischaemia with or without non-rheumatic atrial fibrillation. European Atrial Fibrillation Trial and Dutch T I A Trial Study Groups.

In an attempt to distinguish between the CT characteristics of strokes of presumed cardioembolic origin and strokes caused by arterial disease, a comparison was made between the baseline CT of two prospective cohorts of patients with transient ischaemic attack or minor ischaemic stroke, with (n = 985) or without (n = 2987) non-rheumatic atrial fibrillation (NRAF). Of the patients with NRAF 54% had evidence of cerebral infarction v 41% of the controls (patients with sinus rhythm (SR); odds ratio (OR) 1.7; 95% confidence interval (95% CI) 1.4-1.9). Patients with NRAF more often had multiple infarcts (OR 1.4; 95% CI 1.1-1.8), and more often infarcts that were not related to current neurological symptoms (OR 1.5; 95% CI 1.2-1.8). For symptomatic infarcts, patients with NRAF more often had cortical end zone infarcts (OR 3.1; 95% CI 2.6-3.8) and cortical border zone infarcts (OR 1.9; 95% CI 1.3-2.9) than patients with SR. Conversely, symptomatic small deep infarcts (lacunae) were more often seen in patients with SR (OR 3.9; 95% CI 2.8-5.4). Multivariate analyses showed that all these findings were independent of differences in baseline characteristics between the two study groups. The CT characteristics overlapped and did not allow a reliable distinction between cardioembolic and atherosclerotic causes of stroke in patients with NRAF.

Aged↗

PubMedDate not supplied

The interrelationship between atrial fibrillation and atrial flutter.

For a long time, it has been known that atrial fibrillation and atrial flutter have a close clinical interrelationship. Recent electrophysiological studies, especially mapping studies, have significantly advanced our understanding of this interrelationship. Regarding the relationship of atrial fibrillation with atrial flutter: Atrial fibrillation of variable duration precedes the onset of atrial flutter in almost all instances. During the atrial fibrillation, the functional components needed to complete the atrial flutter reentrant circuit, principally a line of block between the venae cavae, are formed. If this line of block does not form, classical atrial flutter does not develop. If this line of block shortens or disappears, classical atrial flutter disappears. In fact, it is fair to say that the major determinant of whether atrial fibrillation persists or classical atrial flutter develops is whether a line of block forms between the venae cavae. Regarding the relationship of atrial flutter with atrial fibrillation: Studies in experimental models and now in patients have demonstrated that a driver (a rapidly firing focus or a reentrant circuit of very short cycle length) can cause atrial fibrillation by producing fibrillatory conduction to the rest of the atria. When the driver is a stable reentrant circuit of very short cycle length, it is, in effect, a very fast form of atrial flutter. There probably is a spectrum of reentrant circuits of short cycle length, i.e., "atrial flutter," that depend, in part, on where the reentrant circuit is located. When the cycle length of the reentrant circuit is so short that it will only activate small portions of the atria in a 1:1 manner, the rest of the atria will be activated rapidly but irregularly, i.e., via fibrillatory conduction, resulting in atrial fibrillation. In short, there are probably several mechanisms of atrial fibrillation, one of which is due to a very rapid atrial flutter circuit causing fibrillatory conduction. In sum, atrial fibrillation and atrial flutter have an important interrelationship.

Animals↗

PubMed1996

[Electrophysiologic mechanisms of atrial fibrillation].

Atrial fibrillation is the most common arrhythmia in clinical practice. Atrial fibrillation is characterized by a complete disorganization in atrial electrical activity and sinus node pacemaker activity is lost. The physiopathological mechanisms of atrial fibrillation is based on the simultaneous presence of multiple wavelets in the atria. These multiple wavelets are continuously changing in localization, direction and duration resulting in a chaotic electrical activity. This theory has been confirmed by several studies using detailed mapping of the atria during atrial fibrillation. Also, the functional nature of the reentrant circuits during atrial fibrillation has also been demonstrated. For an episode of atrial fibrillation to perpetuate, the wavelength of the cardiac impulse has to be adapted to the length of the atria. Modifications of the wavelength by drugs may result in perpetuation or in termination of the atrial fibrillation episode.

Atrial Fibrillation↗

PubMed1994

[High frequency catheter ablation of left-sided manifest accessory conduction pathways during sinus rhythm and in continuous atrial fibrillation].

Atrial fibrillation is frequently initiated during radiofrequency catheter ablation of accessory pathways. It has been generally believed that initiation of atrial fibrillation may complicate the localization of accessory pathway. Therefore, most centers currently perform cardioversion in order to continue the ablation session. The purpose of the present study was to assess the feasibility and the electrophysiologic criteria for successful radiofrequency catheter ablation of left sided accessory pathways during atrial fibrillation in patients with WPW-syndrome. Radiofrequency ablation was performed in 87 patients with left-sided manifest accessory pathways during atrial fibrillation (n = 16) or during sinus rhythm (n = 71). The criteria for localization of accessory pathways were recording of stable accessory pathway potentials, local ventricular activation preceding the onset of the intrinsic flection of the unipolar electrogram and a QS pattern of the unipolar electrogram. Overall, the accessory pathways were successfully interrupted in 85/87 patients (98%). During the first ablation procedure, abolishing of accessory pathways was achieved in 15 of 16 patients (94%) during atrial fibrillation compared to 64 of 71 patients (90%) during sinus rhythm (n.s.). The total procedure time and fluoro time was significantly shorter during atrial fibrillation than during sinus rhythm (161 +/- 91 min vs. 216 +/- 128 min, p < 0.05, and 31 +/- 24 vs. 41 +/- 26 min. p < 0.05, respectively). Thus, it is feasible and very effective to perform radiofrequency ablation of left-sided manifest accessory pathways during atrial fibrillation. Precise localization of accessory pathway during atrial fibrillation seems even easier than during sinus rhythm as indicated by shorter procedure and fluoro times in the atrial fibrillation group.

Adolescent↗

PubMed2004

Surgery for atrial fibrillation.

Atrial fibrillation is the most common sustained cardiac arrhythmia and is associated with significant morbidity and mortality. Surgical treatment is the most effective means of curing atrial fibrillation. The classic Cox maze procedure eliminates atrial fibrillation in more than 90% of patients and has remained the gold standard in surgery for atrial fibrillation. Despite being highly effective, the complexity of the procedure and long operating time associated with the operation has prevented its widespread application by surgeons. Advances in the understanding of the pathogenesis of atrial fibrillation and development of new ablation technologies have fuelled renewed interest in and development of surgical ablation procedures for atrial fibrillation. These new procedures are simpler and easily reproducible and cure atrial fibrillation in approximately 80% of patients. This article reviews the development of surgery for atrial fibrillation and our experience with the radiofrequency Cox maze III procedure.

Aged↗

PubMed2003

The RACE study in perspective of randomized studies on management of persistent atrial fibrillation.

Atrial fibrillation is the most common sustained cardiac arrhythmia. Treatment strategies are focused on reducing symptoms and minimizing the risks of atrial fibrillation like stroke and heart failure. First choice therapy is the rhythm control strategy, with restoration of sinus rhythm. Drawback of this approach is the low success rate for maintenance of sinus rhythm. Outcome will improve with the use of antiarrhythmic drugs after electrical cardioversion, unfortunately exposing the patient to the risks of life threatening pro-arrhythmia. The second alternative, a rate control strategy, is easy to achieve but it is unknown whether this treatment strategy results in higher morbidity and mortality rates. RACE (RAte Control versus Electrical cardioversion for persistent atrial fibrillation) was a prospective randomized trial comparing both strategies. The primary end point was a composite of death from cardiovascular causes, heart failure, thromboembolic complications, bleeding, pacemaker implants and severe adverse effects of drugs. After a mean follow-up of 2.3 years, the primary end point occurred in 44 of the 256 rate control patients (17.2%) and 60 of the 266 rhythm control patients (22.6%). Other trials as the AFFIRM (Atrial Fibrillation Follow-up Investigation of Rhythm Management), PIAF (Pharmacological Intervention in Atrial Fibrillation) and STAF (Strategies of Treatment of Atrial Fibrillation) also found that rate control was not inferior to rhythm control in terms of morbidity, mortality and quality of life. These four randomized trials demonstrated that a rate control strategy is an acceptable alternative to rhythm control in patients with recurrent atrial fibrillation. For those with severely symptomatic atrial fibrillation, continued rhythm control is unavoidable. For these patients, safer and more effective methods of maintaining sinus rhythm are needed to reduce morbidity related to palpitations and atrial fibrillation-induced heart failure.Furthermore, the randomized studies showed that rhythm control therapy does not prevent stroke. It was observed from RACE that 21 of the 35 thromboembolic complications occurred under rhythm control, the majority while receiving inadequate anticoagulation therapy. Also in AFFIRM, with patients with one or more stroke risk factors, more strokes were present under rhythm control. Therefore, one of the main lesson learned from the randomized studies is that anticoagulation must be continued if stroke risk factors are present even if patients maintain sinus rhythm.

Anti-Arrhythmia Agents↗

PubMed2003

Tedisamil in coronary disease: additional benefits in the therapy of atrial fibrillation?

Atrial fibrillation has recently come into clinical and research focus. In particular, ventricular rate control has been carefully compared with atrial rhythm control. Additionally, the recent discovery of atrial stunning has initiated clinical and research interest in atrial remodeling. Atrial fibrillation is more likely to occur when the atria are damaged by increased fibrosis. The ideal way to prevent atrial fibrillation and the risk of repetition is by tackling the root causes, such as ischemic heart disease, heart failure, and left ventricular hypertrophy. Tedisamil is an unusual antifibrillatory compound that has a novel mechanism of action by inhibiting the transient outward current (Ito) and the repolarizing potassium currents in the sinoatrial node. Tedisamil works acutely against atrial fibrillation. Importantly, atrial fibrillation is often caused by or related to cardiac ischemia, and conversely, ischemia is caused by the increased oxygen demand of atrial fibrillation. Hence, the double properties of tedisamil as a drug that both inhibits atrial fibrillation and acts in an anti-ischemic mode are an attractive basis for future clinical research.

Anti-Arrhythmia Agents↗

PubMed2003

[Catheteer ablation technique of atrial fibrillation].

Atrial fibrillation is the most frequent arrhythmia with a prevalence of 1.7% in the general population and 5% in the population over 65 year old [1], the prevalence in men over 65 years is even 9.1% [2]. Atrial fibrillation is divided dependent on its frequency in intermittent, persisting and chronic. The symptoms and the clinical course are individually very different. Responsible for the initiation of atrial fibrillation are triggers, which initiate atrial fibrillation, and a substrate, that means an atrial myocardium altered by remodelling, which maintains atrial fibrillation. A curative treatment was not available until recently. Different ablation techniques were developed: Linear, focal ablation techniques and the isolation of pulmonary veins. The observation that atrial fibrillation will maintain only in large atria, led to the linear ablation techniques with the goal of reducing the atria functionally. The linear ablations have however a small value because of low success rates and high complication rates. Arrhythmogenic foci are of crucial importance in the initiation of atrial fibrillation, these foci are mostly located in the pulmonary veins. This observation led to the focal ablation in the pulmonary veins, which was left again because of the limitations, however. For some years the isolation of pulmonary veins is performed at some large centers. This paper summarizes the most important techniques, success rates and complications of the pulmonary vein isolation. The present indication and the preinterventional diagnostics are discussed. Due to the constantly improving success rates and decreasing complication rates (pulmonary vein stenosis, thrombembolie, cardiac tamponades, mortality practically) the pulmonary vein isolation is an alternative possibility of treatment which can be considered for a subgroup of patients with drug-resistant, symptomatic atrial fibrillation.

Atrial Fibrillation↗

PubMed2006

Mechanisms of disease: Genetic mechanisms of atrial fibrillation.

Atrial fibrillation is the most common cardiac arrhythmia, and it increases in prevalence with advancing age to about 6% in people older than 65 years. The chance of developing atrial fibrillation at age 40 years or older is about 25% in men and women. This arrhythmia accounts for about one-third of all strokes, and 30% of all patients with atrial fibrillation have a family history of the disease. In 1997, Brugada et al. identified the first locus for familial atrial fibrillation on chromosome 10q22-24 in three different Spanish families. Since that time, seven further loci have been mapped and four relevant genes identified. All these genes encode potassium-channel subunits. The mechanism of action by which all four genes induce atrial fibrillation is via shortening of the action potential duration and atrial effective refractory period. The consistency of the mechanism of action beckons the development of therapy specifically targeted to prevent these molecular events. In addition to monogenic diseases, patients with structural heart disease are predisposed to atrial fibrillation by inherited DNA polymorphisms. The development of chips with hundreds of thousands of single-nucleotide polymorphisms to perform genome-wide scans will elucidate over the next few years the single-nucleotide polymorphisms that predispose to atrial fibrillation. Within the next decade, most of the genes responsible for atrial fibrillation and the single-nucleotide polymorphisms that confer predisposition will probably be identified, and therapies will be developed on the basis of individuals' genomic profiles. In this review I provide an overview of the understanding of the relevant genetic mutations that have been identified so far, and briefly discuss what implications this information might have for practice.

Atrial Fibrillation↗

PubMed2003

[Rationale and management of perioperative atrial fibrillation].

Atrial fibrillation is the most common clinically relevant arrhythmia. Anesthesiologists will be faced with atrial fibrillation of new or undetermined onset at their preoperative evaluation of patients as well as during intra- and post operative care. Because of fast electrophysical and structural remodeling, atrial fibrillation tends to persist and reoccur after successful conversion with increasing time of duration. Therefore, atrial fibrillation with an onset of less than 48 hours should be attempt to convert as soon as diagnostic work up has been made and possible causes have been corrected. New developments of electrophysiological and pharmacological treatment have improved the short term success rate of cardioversion. Further developments might give even more specific treatment options for the individual patient. In contrast, for treatment of chronic atrial fibrillation rate control therapy and thromboembolic prophylaxes seems to be more advisable with a lower risk of drug side effects and stroke. Anticoagulation should be initiated not later than 48 hours after the onset of atrial fibrillation. Finally, the development of implantable devices for the treatment of atrial fibrillation seem to be a promising therapeutic option for patients in end-stage heart diseases.

Atrial Fibrillation↗

PubMed1996

[Drug therapy of atrial fibrillation].

Atrial fibrillation can, clinically, be differentiated into several subgroups. Paroxysmal atrial fibrillation lasts less than 24 hours and is often caused by an autonomic dysregulation. Chronic atrial fibrillation occurs in a reversible and an irreversible form. Atrial fibrillation is frequently observed transiently after cardiac surgery. The therapeutic goal must be clearly defined before treatment is initiated. In patients with a reversible form of chronic atrial fibrillation, sinus rhythm can be restored with class Ia, Ic and III antiarrhythmic drugs. These patients with sinus rhythm benefit from higher cardiac output, fewer thromboembolic complications and fewer symptoms (no palpitations). In patients suffering from an irreversible form of chronic atrial fibrillation the therapeutic aim is control of ventricular rate. Digoxin, beta-blockers (class II) and calcium antagonists (class IV) are successfully used to slow atrioventricular conduction. Patients aged over 65 years should be anticoagulated, since numerous studies have shown a marked decrease in thromboembolic complications with warfarin.

Aged↗

PubMed2006

Echocardiography in atrial fibrillation.

Atrial fibrillation is the most commonly encountered sustained arrhythmia. Echocardiography has augmented the knowledge about etiology and complications of atrial fibrillation. Transthoracic echocardiography allows rapid, safe and comprehensive assessment of cardiac structure and function, and is recommended for all subjects with atrial fibrillation. The use of transesophageal echocardiography has contributed to a better understanding of the thromboembolic risk in patients with atrial fibrillation, especially in the setting of electrical cardioversion. Several investigators have demonstrated the feasibility and safety profile of early cardioversion with short-term anticoagulation in patients with atrial fibrillation and a transesophageal echocardiography negative for atrial thrombi. More recently, transesophageal and intracardiac echocardiography have been employed in patients with atrial fibrillation to monitor percutaneous procedures such as pulmonary veins radiofrequency ablation or left atrial appendage obliteration. In this review the available echocardiographic imaging modalities and their specific role in the evaluation and management in atrial fibrillation are described.

Atrial Fibrillation↗

PubMed1994

[Clinical aspects and prognosis of atrial fibrillation].

Atrial fibrillation is alleged to be one of the most frequently occurring arrhythmia. Many patients with atrial fibrillation are asymptomatic. Others, however, complain of palpitations and paroxysmal atrial tachycardias. And especially in patients with preexisting heart failure, atrial fibrillation can lead to a clear worsening of cardiac output. Not only rheumatic but nonrheumatic atrial fibrillation as well are associated with an increased risk of thromboembolic complications. Arterial hypertension, a history of thromboembolism as well as signs of heart failure are clinical parameters which additionally increase the risk of embolism. On the other hand, this increased risk does not hold true for younger patients with idiopathic atrial fibrillation and is also low in patients with only one additional risk factor. Thus, it would indeed be false to anticoagulate every patient with atrial fibrillation. In each case, a careful individual risk stratification including an extensive history and detailed clinical examination should be performed before deciding on antithrombotic therapy.

Aged↗

PubMed1998

Treatment strategies for atrial fibrillation.

Atrial fibrillation is the most common arrhythmia observed in clinical practice, occurring in 0.4% of the general population and in up to 4% of people greater than 60 years old. It is often associated with other cardiovascular disorders, such as hypertension, coronary artery disease, or cardiomyopathy. Critical evaluation and management of patients with atrial fibrillation requires knowledge of etiology, prognosis, and treatment options of this arrhythmia. On initial presentation, emergency electrical cardioversion should be performed if the patient is hemodynamically unstable. If the patient is stable, initial rate control is recommended, using atrioventricular nodal blocking agents. Further treatment mainly depends upon the duration of the episode. Patients who are in atrial fibrillation <48 hours can be safely cardioverted. Patients who are in atrial fibrillation for >48 hours are commonly anticoagulated for 3 to 4 weeks before and after cardioversion because of the risk of thromboembolism formation in the left atrial appendage. An alternate strategy, which is especially attractive when immediate cardioversion is desired, is transesophageal echocardiography to exclude left atrial thrombus followed by prompt cardioversion. After cardioversion, sinus rhythm can be maintained with class I and III drugs, such as flecainide and propafenone or amiodarone and sotalol. New treatment options, such as atrial defibrillation, atrioventricular junctional ablation, or modification of atrial pacing to prevent atrial fibrillation, are currently under investigation. Although atrial fibrillation is so common in clinical practice, it still remains difficult to treat. Conversion and maintenance to sinus rhythm with antiarrhythmic drug therapy has not shown any improvement in mortality, and some patients may benefit more from ventricular rate control. This review article discusses different treatment strategies for patients with atrial fibrillation.

Anti-Arrhythmia Agents↗

PubMedDate not supplied

Recent advances in the non-surgical management of atrial fibrillation.

Atrial fibrillation is the commonest clinical arrhythmia, and is associated with significant morbidity and mortality. The treatment of choice is to restore and maintain sinus rhythm. Although certain antiarrhythmic drugs are more effective than placebo in maintaining sinus rhythm, recurrence of atrial fibrillation post cardioversion remains common. The use of antiarrhythmic drugs can be associated with serious adverse effects due to their negative inotropic and proarrhythmic effects. Radiofrequency ablation of the AV junction is a safe and effective palliative treatment option in patients who have failed drug therapy. Ventricular rate control without the need for permanent pacing can be achieved by AV nodal modification using radiofrequency energy. There is also interest in the role of catheter ablation as a possible curative procedure for atrial fibrillation. Atrial pacing can reduce the incidence of atrial fibrillation in certain subgroups of patients. Finally, low energy intracardiac atrial defibrillation has been shown to be feasible in humans.

Anti-Arrhythmia Agents↗