Rate of conversion and recurrence after sotalol treatment in patients with direct current-refractory atrial fibrillation

BACKGROUND

A number of patients with persistent atrial fibrillation (AF) will not have sinus rhythm (SR) restored by direct current (DC) cardioversion.

HYPOTHESIS

In patients with DC-refractory AF, oral pretreatment with sotalol increases the success rate at DC cardioversion.

METHODS

Consecutive patients with persistent AF, refractory at a first DC cardioversion, were prospectively included. A comparative group of patients with AF not refractory at DC cardioversion was studied. Oral sotalol treatment was started after unsuccessful DC cardioversion and given at least 7 days before renewed cardioversion. Four weeks after cardioversion, an electrocardiogram was performed.

RESULTS

In all, 53 patients were enrolled in the study. Forty-three (81%) in the sotalol group regained sinus rhythm (SR): 10 (19%) of these converted pharmacologically and 33 (62%) after a second DC cardioversion; SR was never restored in 10 patients (19%). After 4 weeks, SR was maintained in 29 patients (67%). The comparative group included 132 patients and differed significantly from the DC-refractory patients only with regard to weight. After 4 weeks, SR was maintained by 50 patients (37%) in this group.

CONCLUSIONS

In patients with persistent AF refractory to DC cardioversion, oral pretreatment with sotalol results in a high rate of SR restoration, either pharmacologically or by DC cardioversion. Maintenance of SR at 4 weeks is of sufficient clinical relevance to consider this treatment option in patients with AF refractory to DC cardioversion.

Role of Rac1 GTPase activation in atrial fibrillation

OBJECTIVES

We aimed to study the role of Rac1 GTPase in atrial fibrillation (AF).

BACKGROUND

The signal transduction associated with AF is incompletely understood. We hypothesized that activation of Rac1 GTPase contributes to the pathogenesis of AF via activation of nicotinamide adenine dinucleotide phosphate (NADPH) oxidase and production of reactive oxygen species.

METHODS

Old mice with cardiac-specific overexpression of constitutively active V12Rac1 (RacET) were compared with wild-type (WT) and WT undergoing transaortic constriction (TAC). In addition, samples of human left atrial appendages were analyzed in patients with sinus rhythm (SR) compared with patients with permanent AF matched for atrial diameter.

RESULTS

At age 16 months, 75% of RacET but no WT or TAC mice showed AF. Treatment of RacET with statins for 10 months did not alter weight or fibrosis of atria or ventricles but decreased cardiac Rac1 and NADPH oxidase activity and reduced the incidence of AF by 50%. The left atria of patients with AF showed increased fibrosis, up-regulation of NADPH oxidase activity, a 4-fold increase of Rac1 total protein and membrane expression as well as up-regulation of Rac1 activity.

CONCLUSIONS

Chronic cardiac overexpression of Rac1 represents a novel mouse model for AF. Rac1 GTPase contributes to the pathogenesis of AF and identifies a target for the prevention and treatment of AF.

A review of the investigational antiarrhythmic agent dronedarone

Arrhythmias are a major cause of morbidity and mortality, and atrial fibrillation is the most widespread disorder of cardiac rhythm. Amiodarone is an effective antiarrhythmic agent that has been in clinical use for about 20 years. It is effective for multiple types of arrhythmias, including atrial fibrillation, and has a low incidence of cardiac adverse events, including Torsade de Pointes. It has many noncardiac adverse effects that are serious and limit its long-term use. Dronedarone is an investigational antiarrhythmic agent that is designed to have similar cardiac effects to amiodarone but with fewer adverse effects. This review presents some of the animal and human studies that evaluate the effects of dronedarone.

Ablation should not be first-line therapy for the treatment of atrial fibrillation

The introduction of new techniques into medical practice frequently results in uncertainty for potential referring physicians and patients alike. The development of safe and effective percutaneous techniques for the cure of symptomatic Wolff-Parkinson-White (WPW) syndrome quickly led to near-elimination of the use of cardiac surgery and antiarrhythmic drugs to treat this proarrhythmic condition, and is justly regarded as a triumph of innovation by both electrophysiologists and biomedical engineers. The introduction of balloon angioplasty also led to a reduction in the number of patients referred for surgical procedures, although with arguably less rationale. An excess of popular enthusiasm among patients and physicians for this procedure made critical debate (continuing in academic circles) moot, at least in the USA. In this paper, I will argue that radiofrequency ablation for the treatment of atrial fibrillation is more akin to the use of angioplasty and less like the treatment of WPW, and cannot be justified as first-line therapy. Unfortunately, excessively optimistic characterization of ablation for atrial fibrillation is obscuring critical issues that ought to be considered by electrophysiologists, referring physicians and patients.

Atrial fibrillation in Australian general practice

The BEACH program is a continuous national study of general practice activity in Australia. This article provides an analysis of the encounters where atrial fibrillation was managed from April 2004 to March 2006. This synopsis provides a backdrop against which articles in this issue of Australian Family Physician can be further considered.

[Pharmacological therapy for atrial fibrillation after cardiac surgery]

Atrial fibrillation (AF) is one of the most common complications following cardiac surgery. AF is associated with an increased risk of stroke, prolonged hospitalization and increased medical costs. Risk factors of post-operative AF are valvular surgery, advanced age, and pre-operative history of AF. Postoperative AF occurs most frequently at 2 days after the surgery and rarely after 7 post-operative days. Most of post-operative AF is short-lived and terminates until discharge. Because of short-lived nature, rate control with beta-blockers or Ca antagonists is the treatment of choice. Beta-blockers, amiodarone and sotalol are effective in preventing post-operative AF when given before the surgery and for 7 days post-operatively. Anticoagulation with heparin should be given to the patients when thromboembolic risk is high.

Do statins have an antiarrhythmic activity?

Sudden cardiac death, which is mainly associated with the presence of life-threatening ventricular arrhythmias, is a common 'killer' among patients with coronary artery disease. Moreover, atrial fibrillation is the most common arrhythmia encountered in the clinical practice. The beneficial effect of statins on cardiovascular morbidity and mortality is well-established, while the exact role of this class of drugs against arrhythmias remains unclear. This review discusses the effect of statin treatment on arrhythmias that are commonly seen in the clinical setting. The underlying pathophysiological mechanisms are also overviewed. Compelling evidence from the majority of the studies reviewed shows that statins exhibit a protective effect against the occurrence of ventricular arrhythmias and atrial fibrillation.

Management of atrial fibrillation

BACKGROUND

Atrial fibrillation affects a significant proportion of the Australian population, affecting approximately 5% of people over 65 years of age.

OBJECTIVE

This article provides an approach to the management of this common arrhythmia.

DISCUSSION

During initial assessment, it is important to identify and treat any comorbid conditions that may contribute to atrial fibrillation. The clinician must then determine an appropriate anticoagulation regimen and choice of either a rate or rhythm control approach. Anticoagulation can be with either warfarin or aspirin, with the decision based on an assessment of the patient's thromboembolic risk. Rate and/or rhythm control can be achieved pharmacologically, with device based therapy or with newer catheter ablation techniques. A combination of these differing approaches may be required in patients in whom it is difficult to achieve and maintain therapeutic goals.

New Pharmacologic Approaches to Prevent Thromboembolism in Patients with Atrial Fibrillation

Atrial fibrillation (AF) is associated with a 6 fold increased risk for ischemic stroke. Observational studies suggest that one in four to five strokes is due to AF. Depending on the risk profile of an individual patient, the yearly risk for ischemic stroke is between 2% and 14%. AF is accompanied by an increased propensity for atrial clot formation due to a combination of decreased atrial blood flow, increased activity of the platelet/plasmatic coagulation system and prothrombotic changes at the atrial endocardium. This review summarizes the current guidelines for thromboembolic prevention in patients with AF. In many cases, continuous oral anticoagulation therapy (OAT) with vitamin K antagonists (VitKAs) is indicated if AF is accompanied by more than one additional risk factor for thromboembolic complications. However, therapeutic range of VitKAs (Phenprocoumon, Warfarin, and others), the most commonly used oral anticoagulants, is narrow and their use requires regular anticoagulation monitoring. Possibly due to these limitations, about one third of eligible patients are not treated with VitKAs. Furthermore, in many treated patients OAT is not well controlled. Thus, in clinical practice anticoagulation therapy in AF is suboptimal. Therefore, new and more convenient pharmacologic approaches to prevent thromboembolism with i.e. direct thrombin inhibitors (DTI), synthetic polysaccharides (factor Xa Inhibitors), and others are discussed, and their possible future role in the treatment of AF is evaluated.

[Effects of angiotensin converting enzyme inhibitor on the expression of angiotensin converting enzyme 2 in atrium of patients with atrial fibrillation]

OBJECTIVE

To investigate the expression of angiotensin converting enzyme 2 (ACE2) and the changes treated with angiotensin converting enzyme inhibitor (ACEI), and its signal transduction pathway.

METHODS

Atrial tissues were obtained from 47 patients with RHD undergoing cardiac surgery. The mRNA of ACE2 and ACE were semi-qualified by RT-PCR and normalized to the gene beta-actin. Western blot analysis was employed to examine the expressions of ACE2, ACE, ERK1/2 and phosphorylated ERK (pERK1/2). The atrial tissue angiotensin II (Ang II) content was determined by radioimmunoassay detection.

RESULTS

The expression of ACE2 was significantly decreased (P < 0.05), the expression of ACE and pERK1/2 were significantly increased (P < 0.05), and the level of atrial tissue Ang II was significantly increased in patients with chronic atrial fibrillation group (CAF) compared with sinus rhythm group (SR) (P < 0.05). Compared with CAF patients treated without ACEI, the expression of ACE2 significantly increased (P < 0.01), and the relative activity of ERK1/2 significantly decreased (P < 0.05), whereas the expression of ACE and the level of atrial tissue Ang II remained unchanged in CAF patients treated with ACEI.

CONCLUSIONS

The study suggested that the dysequilibrium of ACE/ACE2 might play an important role in the process of atrial fibrillation, which may be related to the activation of ERK1/2 pathway. The clinical effect of long-term treatment of ACEI maybe associated with elevated ACE2 expression but not ACE expression.

The Clinical Noncompliance of Oral Sotalol/Magnesium for Prophylactic Treatment of Atrial Fibrillation After Coronary Artery Bypass Grafting

BACKGROUND

Postoperative atrial fibrillation has been refractory to many attempted pharmacologic prevention methods and, when effective, side effects have been described. The present aim was to study the clinical compliance of a suggested prophylactic treatment, oral sotalol, and magnesium.

METHODS

Coronary-bypass patients without clinical contraindications to receive oral sotalol (80 mg twice daily) and magnesium supplementation were enrolled (n = 49) with an intention-to-treat strategy and being compared with a matched control group (n = 844). A protocol listed exclusion criteria of clinical compliance that was postoperatively evaluated prior to and during treatment.

RESULTS

Twenty-seven of the 49 enrolled patients (55%) were compliant to sustain the treatment according to the protocol. The remaining patients were postoperatively excluded, mainly because of hemodynamic reasons, of whom 14 were noncompliant to initiate any treatment. The AF occurrence in the compliant group was 7% versus 36% in noncompliant patients (p = 0.035), and 24% in the control group (p = 0.076). However, with an intention-to-treat policy the overall AF incidence became 18%. The subgroups of enrolled patients demonstrated skewing phenomena. The noncompliant group had higher requirement for inotropic support (p = 0.029) and longer aortic cross-clamp time (p = 0.048) compared to compliant patients. Further, the body weight of noncompliant patients was markedly lower than in the compliant counterpart (p = 0.015).

CONCLUSIONS

The tested treatment protocol showed limited compliance among routine cardiac-surgery patients, and further, introduced a biased selection of patients that skewed the results and may have partly explained the treatment effect.

Cardioversion of persistent atrial fibrillation by a combination of atrial specific and non-specific class III drugs in the goat

OBJECTIVE

In electrically remodeled atria the effect of blockers of the delayed rectifier K+ current I(Kr) on repolarization is reduced, whereas the efficacy of 'early' class III drugs (I(Kur)/I(to)/I(Kach) blockers) is enhanced. We evaluated the electrophysiological and antifibrillatory effects of AVE0118, dofetilide, and ibutilide (alone and in combination) on persistent atrial fibrillation (AF) in the goat.

METHODS AND RESULTS

The effects of separate and combined administration of AVE0118, dofetilide, and ibutilide were determined before and after 48 h of AF. AVE0118 alone markedly prolonged the atrial refractory period (400 ms cycle length) (AERP400) before and after 48 h of AF. The prolongation of AERP(400) by dofetilide and ibutilide, respectively, was reduced by AF from 22+/-2 to 7+/-2 ms (p<0.01) and 25+/-5 to 5+/-2 ms (p=0.01). Pre-treatment with AVE0118 restored the prolongation of AERP400 by dofetilide or ibutilide (to 20+/-3 and 30+/-6 ms; p<0.01). This effect was atrial specific since the QT-interval was not changed. The antifibrillatory action was evaluated in 10 goats that were in persistent AF for 57+/-7 days. Dofetilide (20 microg/kg/h) or ibutilide (4 mg/h) alone restored sinus rhythm in only 20% of the animals. AVE0118 (1, 3 and 10 mg/kg/h) [DOSAGE ERROR CORRECTED] terminated AF in 11, 30, and 60%, respectively. Additional infusion of I(Kr) blockers caused an additional number of cardioversions, resulting in a final cardioversion rate of 56, 80, and 100%, respectively. AVE0118 alone prolonged the AF cycle length (AFCL) while the conduction velocity during AF (CV(AF)) remained unchanged (70+/-1 vs. 68+/-2 cm/s; p=0.3). Addition of dofetilide or ibutilide caused a synergistic increase in AFCL and a slight increase in CV(AF) to 74+/-1 cm/s (p<0.001). The length of the reentrant trajectories increased from 7.6+/-0.3 (control) to 11.6+/-0.5 cm after AVE0118 alone (p<0.001) and 14.8+/-0.8 cm after addition of dofetilide or ibutilide (p<0.001).

CONCLUSIONS

In electrically remodeled atria, blockade of I(Kur)/I(to)/I(KAch) restored the class III action of I(Kr) blockers. Persistent AF could be effectively cardioverted by infusion of a combination of AVE0118 and dofetilide or ibutilide. This antifibrillatory action was associated with an almost twofold lengthening of the intra-atrial pathways for reentry.

Prevention of Ischemic Stroke: Antithrombotic Therapy in Cardiac Embolism

Ischemic stroke secondary to cardiac disease accounts for approximately 30% of all stroke subtypes and it may be due to a large list of conditions. Stroke secondary to heart disease causes more severe deficits, higher mortality, and increased costs that other stroke subtypes. Therefore, proper identification of cardioembolic stroke is crucial for adequate selection of optimal preventive strategies. Identification of stroke prone individuals with heart disease could also have an important therapeutic impact. This manuscript reviews the interaction between the heart and brain with a particularly emphasis in the current state of older and newer antithrombotic drugs for stroke prevention in patients with atrial fibrillation. Other neuro-cardiological issues reviewed include current antithrombotic strategies in patients with a host of heart conditions which include pacemakers, acute myocardial infarction, congestive heart failure, cardiac procedures, patent foramen ovale, valve disease, endocarditis, or cardiac tumours.

Amiodarone Therapy for Atrial Rhythm Control: Insights Gained From a Single Center Experience

INTRODUCTION

Amiodarone has been advocated as an effective "long-term" therapy for atrial rhythm control in patients with atrial fibrillation (AF). We sought to assess the sustainability of this therapeutic strategy.

METHODS AND RESULTS

Retrospective analysis of a consecutive, single-center cohort (n = 168) with symptomatic AF who were treated with amiodarone and followed for 3 years. The incidence of amiodarone cessation was evaluated at 1, 2, and 3 years and attributed principally to drug inefficacy, intolerance, or toxicity. A gradual diminution in the number of patients on therapy was observed, such that by 3 years, only 45% remained. This was attributable to inefficacy (25%), intolerance (12%), or toxicity (18%). Pulmonary toxicity was surprisingly common, occurring in at least 7% of patients.

CONCLUSIONS

These data challenge the notion of amiodarone as a reasonable "destination" therapy for AF.

A patient decision aid to support shared decision-making on anti-thrombotic treatment of patients with atrial fibrillation: randomised controlled trial

OBJECTIVE

To determine the efficacy of a computerised decision aid in patients with atrial fibrillation making decisions on whether to take warfarin or aspirin therapy.

DESIGN

Two-armed open exploratory randomised controlled trial.

SETTING

Two research clinics deriving participants from general practices in Northeast England.

PARTICIPANTS

109 patients with atrial fibrillation aged over 60.

INTERVENTIONS

Computerised decision aid applied in shared decision-making clinic compared to evidence-based paper guidelines applied as direct advice.

MAIN OUTCOME MEASURES

Primary outcome measure was the decision conflict scale. Secondary outcome measures included anxiety, knowledge, decision-making preference, treatment decision, use of primary and secondary care services and health outcomes.

RESULTS

Decision conflict was lower in the computerised decision aid group immediately after the clinic; mean difference -0.18 (95% CI -0.34 to -0.01). Participants in this group not already on warfarin were much less likely to start warfarin than those in the guidelines arm (4/16, 25% compared to the guidelines group 15/16, 93.8%, RR 0.27, 95% CI 0.11 to 0.63).

CONCLUSIONS

Decision conflict was lower immediately following the use of a computerised decision aid in a shared decision-making consultation than immediately following direct doctor-led advice based on paper guidelines. Furthermore, participants in the computerised decision aid group were significantly much less likely to start warfarin than those in the guidelines arm. The results show that such an approach has a positive impact on decision conflict comparable to other studies of decision aids, but also reduces the uptake of a clinically effective treatment that may have important implications for health outcomes.

Qualitative methods in a randomised controlled trial: the role of an integrated qualitative process evaluation in providing evidence to discontinue the intervention in one arm of a trial of a decision support tool

OBJECTIVE

To understand participants' experiences and understandings of the interventions in the trial of a computerised decision support tool in patients with atrial fibrillation being considered for anti-coagulation treatment.

DESIGN

Qualitative process evaluation carried out alongside the trial: non-participant observation and semistructured interviews.

PARTICIPANTS

30 participants aged >60 years taking part in the trial of a computerised decision support tool.

RESULTS

Qualitative evidence provided the rationale to undertake a decision to discontinue one arm of the trial on the basis that the intervention in that arm, a standard gamble values elicitation exercise was causing confusion and was unlikely to produce valid data on participant values.

CONCLUSIONS

Qualitative methods used alongside a trial allow an understanding of the process and progress of a trial, and provide evidence to intervene in the trial if necessary, including evidence for the rationale to discontinue an intervention arm of the trial.

Risk of major bleeding with concomitant dual antiplatelet therapy after percutaneous coronary intervention in patients receiving long-term warfarin therapy

STUDY OBJECTIVES

To characterize the safety of concomitant aspirin, clopidogrel, and warfarin therapy after percutaneous coronary intervention (PCI), and to identify patient characteristics that increase the risk of hemorrhage.

DESIGN

Retrospective, matched cohort study.

SETTING

Academic medical center and affiliated outpatient offices.

PATIENTS

The active group consisted of 97 patients who underwent PCI from January 1, 2000-September 30, 2005, and received warfarin, aspirin, and clopidogrel; the control group consisted of 97 patients who were individually matched to patients in the active group by procedure type, procedure year, age, and sex. Control patients received aspirin and clopidogrel.

MEASUREMENTS AND MAIN RESULTS

Clinical data were collected from inpatient records, outpatient physician office records, and telephone surveys administered to patients or caregivers. The primary end point was major bleeding. The median duration of follow-up after index procedure was 182 days (range 0-191 days) in the active group and 182 days (range 0-213 days) in the control group. Fifty-seven (59%) of the 97 patients in the active group received warfarin for atrial fibrillation. There were 14 major bleeds in the active group (including 1 death) and 3 major bleeds in the control group during the study period. Mean international normalized ratio at the time of bleeding was 3.4. Hazard ratio for major bleeding was 5.0 in patients receiving warfarin therapy (95% confidence interval 1.4-17.8, p=0.012). Aspirin dose, age, sex, body mass index, history of hypertension, diabetes mellitus, intraprocedural glycoprotein IIb-IIIa or anticoagulant type, and postprocedural anticoagulant use did not have a significant effect on the risk of major bleeding.

CONCLUSION

Warfarin was an independent predictor of major bleeding after PCI in patients receiving dual antiplatelet therapy. Prospective data to further characterize the safety of concomitant warfarin and dual antiplatelet therapy after PCI are needed.

The effects of statins and renin-angiotensin system blockers on atrial fibrillation recurrence following antral pulmonary vein isolation

INTRODUCTION

Ablation has emerged as a major treatment option for atrial fibrillation (AF). However, this procedure is limited by a significant rate of AF recurrence. We aimed to examine the effects of statins, angiotensin-converting enzyme inhibitors (ACE-I), and angiotensin receptor blockers (ARB) on the recurrence rate of AF following ablation.

METHODS

We conducted a retrospective study of 177 consecutive patients (mean age = 56 +/- 11 yrs, 69% males) who underwent ablation for paroxysmal (n = 132) or persistent AF (n = 45). Patients were treated with ACE-I (n = 31) or ARB (n = 18) or statins (n = 50) prior to ablation and for the duration of follow-up.

RESULTS

After a mean follow-up of 13.8 +/- 8.6 months, 72% of patients were free of AF. For patients taking statins, 33 of 50 (60%) were free of AF. In patients treated with ACE-I, 17 of 31 (55%) were free from AF, while in the group of patients treated with ARB, 17 of 18 (94%) were free from AF. Using Cox regression analysis to correct for baseline variables, treatment with statins did not decrease the recurrence rate (HR = 1.10 [95% CI: 0.55-2.27] p = 0.79); nor did treatment with renin angiotensin system (RAS) blockers (HR 0.94 [95% CI: 0.46-1.93] p = 0.87). However, subgroup analysis showed that treatment with ARB was associated with a trend towards lower AF recurrence [HR 0.17, (95% CI: 0.02-1.34) p = 0.09].

CONCLUSIONS

Even though statins and RAS blockers possess anti-inflammatory properties, they did not decrease the recurrence of AF following ablation. However, the subset of patients taking ARB exhibited a trend towards lower AF recurrence. Larger, randomized studies are needed to address this observation.

Long-Term Progression and Outcomes With Aging in Patients With Lone Atrial Fibrillation

BACKGROUND

The long-term natural history of lone atrial fibrillation is unknown. Our objective was to determine the rate and predictors of progression from paroxysmal to permanent atrial fibrillation over 30 years and the long-term risk of heart failure, thromboembolism, and death compared with a control population.

METHODS AND RESULTS

A previously characterized Olmsted County, Minnesota, population with first episode of documented atrial fibrillation between 1950 and 1980 and no concomitant heart disease or hypertension was followed up long term. Of this unique cohort, 76 patients with paroxysmal (n=34), persistent (n=37), or permanent (n=5) lone atrial fibrillation at initial diagnosis met inclusion criteria (mean age at diagnosis, 44.2+/-11.7 years; male, 78%). Mean duration of follow-up was 25.2+/-9.5 years. Of 71 patients with paroxysmal or persistent atrial fibrillation, 22 had progression to permanent atrial fibrillation. Overall survival of the 76 patients with lone atrial fibrillation was 92% and 68% at 15 and 30 years, respectively, similar to 86% and 57% survival for the age- and sex-matched Minnesota population. Observed survival free of heart failure was slightly worse than expected (P=0.051). Risk for stroke or transient ischemic attack was similar to the expected population risk during the initial 25 years of follow-up but increased thereafter (P=0.004), although CIs were wide. All patients who had a cerebrovascular event had developed > or = 1 risk factor for thromboembolism.

CONCLUSIONS

Comorbidities significantly modulate progression and complications of atrial fibrillation. Age or development of hypertension increases thromboembolic risk.