An Argument for Maintenance of Sinus Rhythm in Patients With Atrial Fibrillation

Atrial Fibrillation in Heart Failure US Ambulatory Cardiology Practices and the Potential for Uptake of Catheter Ablation: An National Cardiovascular Data Registry (NCDR®) Research to Practice (R2P) Project

Background

Atrial fibrillation (AF) and heart failure with reduced ejection fraction frequently coexist. The AATAC (Ablation versus Amiodarone for Treatment of persistent Atrial fibrillation in patients with Congestive heart failure and an implantable device) trial suggests that catheter ablation may benefit these patients. However, applicability to contemporary ambulatory cardiology practice is unknown.

Methods and Results

Using the outpatient National Cardiovascular Data Registry^® Practice Innovation and Clinical Excellence Registry, we identified participants meeting AATAC enrollment criteria between 2013 and 2014. Treatment with medications and procedures was assessed at registry inclusion. From 164 166 patients with AF and heart failure, 8483 (7%) patients potentially met AATAC inclusion criteria. Eligible subjects, compared to AATAC trial participants, were older (mean age, 71.2±11.4 years) and had greater comorbidity (coronary artery disease 79.2%, hypertension 82.4%, and diabetes mellitus 31.8%). AF was predominantly paroxysmal (65.5%), rather than persistent/permanent (16.7%) or new onset (17.8%), whereas all patients in the AATAC trial had persistent AF. Commonly used atrioventricular‐nodal blocking agents were carvedilol (71.2%), digoxin (31.9%), and metoprolol (27.1%). Rhythm control with anti‐arrhythmic drugs was reported in 29.0% of AATAC eligible patients (predominantly amiodarone [24.6%]) and 9.3% had undergone catheter ablation. Patients who underwent ablation were more likely to be younger and have less comorbidities than those who did not.

Conclusions

Among the contemporary ambulatory AF/heart failure with reduced ejection fraction population, treatment is predominantly rate control with few catheter ablations. Application of AATAC findings has the potential to markedly increase the use of catheter ablation in this population, although significant differences in clinical profiles might influence ablation outcomes in practice.

Association of Proteinuria and Incident Atrial Fibrillation in Patients With Intact and Reduced Kidney Function

BACKGROUND

Early evidence suggests proteinuria is independently associated with incident atrial fibrillation (AF). We sought to investigate whether the association of proteinuria with incident AF is altered by kidney function.

METHODS AND RESULTS

Retrospective cohort study using administrative healthcare databases in Ontario, Canada (2002-2015). A total of 736 666 patients aged ≥40 years not receiving dialysis and with no previous history of AF were included. Proteinuria was defined using the urine albumin-to-creatinine ratio (ACR) and kidney function by the estimated glomerular filtration rate (eGFR). The primary outcome was time to AF. Cox proportional models were used to determine the hazard ratio for AF censored for death, dialysis, kidney transplant, or end of follow-up. Fine and Grey models were used to determine the subdistribution hazard ratio for AF, with death as a competing event. Median follow-up was 6 years and 44 809 patients developed AF. In adjusted models, ACR and eGFR were associated with AF (P<0.0001). The association of proteinuria with AF differed based on kidney function (ACR × eGFR interaction, P<0.0001). Overt proteinuria (ACR, 120 mg/mmol) was associated with greater AF risk in patients with intact (eGFR, 120) versus reduced (eGFR, 30) kidney function (adjusted hazard ratios, 4.5 [95% CI, 4.0-5.1] and 2.6 [95% CI, 2.4-2.8], respectively; referent ACR 0 and eGFR 120). Results were similar in competing risk analyses.

CONCLUSIONS

Proteinuria increases the risk of incident AF markedly in patients with intact kidney function compared with those with decreased kidney function. Screening and preventative strategies should consider proteinuria as an independent risk factor for AF.

Antiarrhythmic Drug Therapy for Rhythm Control in Atrial Fibrillation

Atrial fibrillation (AF) is the most common sustained cardiac arrhythmia and affects over 33 million people worldwide. AF is associated with stroke and systemic thromboembolism, unpleasant symptoms and reduced quality of life, heart failure, and increased mortality, and treatment of AF and its complications are associated with significant cost. Antiarrhythmic drugs (AADs) can suppress AF, allowing long-term maintenance of sinus rhythm, and have the potential to relieve symptoms and reverse or prevent adverse effects associated with AF. However, large randomized controlled studies evaluating use of AADs have not demonstrated a clear benefit to maintaining sinus rhythm, and AADs often have significant limitations, including a modest rate of overall success at maintaining sinus rhythm, frequent side effects, and potentially life-threatening toxicities. Although some of the currently available AADs have been available for almost 100 years, better tolerated and more efficacious AADs have recently been developed both for long-term maintenance of sinus rhythm and for chemical cardioversion of AF to sinus rhythm. Advances in automated AF detection with cardiac implantable electronic devices have suggested that AADs might be useful for suppressing AF to allow safe discontinuation of anticoagulation in select patients who are in sinus rhythm for prolonged periods of time. AADs may also have synergistic effects with catheter ablation of AF. This review summarizes the pharmacology and clinical use of currently available AADs for treatment of AF and discusses novel AADs and future directions for rhythm control in AF.

[Hundred years of atrial fibrillation: current knowledge and perspectives]

Atrial fibrillation (AF) is the most common sustained arrhythmia in general population. AF in humans was first described in 1903. Gradually, it has been well appreciated that AF is notjust an acceptable alternative for normal rhythm but rather a serious threat, related to increased mortality and cardiovascular morbidity. AF can precipitate or worsen pre-existing heart failure, may cause the development of tachycardiomyopathy and is an independent risk factor for thromboembolic events, most frequently stroke. It has long been believed that rhythm control is the best therapy for AF. Nowadays there is a clear scientific proof that rhythm control offers no benefit over frequency control, at least for older patients, even with advanced left ventricular dysfunction. However, optimal treatment for younger, highly symptomatic, otherwise healthy AF patients has not been designed. Available antiarrhythmics have considerable proarrhythmic potential or organ toxicity, and new safer drugs are under investigation. Nonpharmacological approaches, namely RF-catheter ablation, are rapidly developing. Prevention of thromboembolism is imperative, and new safer oral anticoagulants have been intensively investigated. Recent randomized studies (PIAF, RACE, STAF, AFFIRM, HOT-CAFE) did not solve the issue of optimal arrhythmia treatment, but they emphasized the prevention of thromboembolism based on risk factors, and not on AF type, mainly because asymptomatic episodes of AF may not be clinically recognised.

Dronedarone

Amiodarone is the most effective antiarrhythmic drug for maintaining sinus rhythm for patients with atrial fibrillation. Extra-cardiac side effects have been a limiting factor, especially during chronic use, and may offset its benefits. Dronedarone is a noniodinated benzofuran derivative of amiodarone that has been developed for the treatment of atrial fibrillation and atrial flutter. Similar to amiodarone, dronedarone is a potent blocker of multiple ion currents, including the rapidly activating delayed-rectifier potassium current, the slowly activating delayed-rectifier potassium current, the inward rectifier potassium current, the acetylcholine activated potassium current, peak sodium current, and L-type calcium current, and exhibits antiadrenergic effects. It has been studied for maintenance of sinus rhythm and control of ventricular response during episodes of atrial fibrillation. Dronedarone reduces mortality and morbidity in patients with high-risk atrial fibrillation, but may be unsafe in those with severe heart failure. This article will review evidence of safety and effectiveness of dronedarone in patients with atrial fibrillation.

Sex differences in the relationship between amiodarone use and the need for permanent pacing in patients with atrial fibrillation

BACKGROUND

Amiodarone use was associated with an increased need for pacemaker insertion in a retrospective study of patients with atrial fibrillation (AF) and prior myocardial infarction. The aims of this study were to determine prospectively whether amiodarone increases the need for pacemakers in a general population of patients with AF and whether this effect is modified by sex.

METHODS

The study included 1005 patients with new-onset AF who were enrolled in the Fibrillation Registry Assessing Costs, Therapies, Adverse events, and Lifestyle (FRACTAL). Multivariable Cox regression models, including time-dependent covariates accounting for medication exposure, were used to evaluate the risk of pacemaker insertion associated with amiodarone use.

RESULTS

Amiodarone use was associated with an increased risk of pacemaker insertion (hazard ratio [HR], 2.01; 95% confidence interval [CI], 1.08-3.76) after adjustment for age, sex, atrial flutter, coronary artery disease, heart failure, and hypertension. The effect of amiodarone use was modified by sex, with a significant risk in women but not in men (HR, 4.69; 95% CI, 1.99-11.05 vs HR, 1.05; 95% CI, 0.42-2.58 [P = .02]). This interaction remained significant after adjustment for weight, body mass index, weight-adjusted amiodarone dose, and use of other antiarrhythmic or rate control drugs.

CONCLUSION

The risk of bradyarrhythmia requiring pacemaker insertion associated with amiodarone use for AF is significantly greater in women than in men, independent of weight or body mass index.

New concepts for old drugs to maintain sinus rhythm in patients with atrial fibrillation

Atrial fibrillation (AF) is a chronic, often progressive disease. Despite the ongoing concerted effort to improve AF therapy, often there is no remedy for curing AF and preventing the deleterious effects of the arrhythmia on health. Antiarrhythmic drug therapy is likely to remain the mainstay of therapy for many patients in the foreseeable future. Available antiarrhythmic drugs are moderately effective, which is important for patients who respond, especially given the chronic and often progressive nature of the disease. This article describes emerging concepts under clinical evaluation that attempt to improve the safety of available antiarrhythmic drugs in the treatment of recurrent AF. Two concepts are reviewed: (1) combination of an antiarrhythmic drug with a calcium channel blocker to reduce proarrhythmic side effects, and (2) "intelligent" reduction of the duration of antiarrhythmic drug therapy targeted to periods of symptomatic or likely AF recurrence.

Restoring normal sinus rhythm in atrial fibrillation : evidence from pharmacologic therapy and catheter ablation trials

Although clinical evidence indicates that many of the electrophysiologic and functional changes associated with atrial fibrillation (AF) can be reversed by maintaining normal sinus rhythm (NSR), a series of large-scale randomized trials failed to demonstrate that this strategy provides a survival advantage. These studies have methodologic limitations, however, that restrict their applicability to the entire AF population. Invasive techniques, including percutaneous catheter ablation and the surgical Maze procedure, offer the potential to reduce the frequency of and in some cases cure AF, although there are serious associated risks. The development and refinement of these techniques have improved outcomes, and they now represent a viable early option for select AF patients. In light of its manifest benefits, the restoration and maintenance of NSR through pharmacologic or nonpharmacologic treatment should remain the therapeutic objective for many AF patients.