Comparison of antiarrhythmic drug therapy and radiofrequency catheter ablation in patients with paroxysmal atrial fibrillation: a randomized controlled trial

Rhythm control for management of patients with atrial fibrillation: balancing the use of antiarrhythmic drugs and catheter ablation

Antiarrhythmic drug (AAD) therapy may be beneficial for patients with symptoms attributable to atrial fibrillation despite adequate rate control. The limited long-term efficacy of AAD and the relatively large proportion of patients discontinuing therapy because of side effects led to the development of nonpharmacological therapies to achieve rhythm control. Pressing questions remain about the effect of ablation therapy on long-term patient outcomes. Based on recent clinical trials and meta-analyses, ablation appears more effective and possibly safer than AAD for long-term maintenance of sinus rhythm in selected patients, but the evidence is insufficient to recommend ablation in preference to drug therapy as the first AAD therapy for the majority of patients in whom a rhythm control strategy is justified. Herein, we review the most current evidence supporting the use of AAD and catheter ablation in atrial fibrillation.

[Catheter ablation of atrial fibrillation. Pulmonary vein isolation by using a new multipolar ablation catheter]

Catheter ablation of atrial fibrillation (AF) is an established therapeutical option, particularly in treatment of paroxysmal atrial fibrillation. This paper presents the results of using the PVAC multi-electrode ablation catheter (PVAC®, Medtronic Ablation Frontiers, Carlsbad, CA, USA). In 253 patients with paroxysmal or persistant AF, 1051 pulmonary veins were isolated, including ablation of 34 left common ostia and 1 right common ostium. Except one vein, all pulmonary veins in all patients were successfully isolated. In 23 patients with documented typical atrial flutter, the right atrial isthmus was additionally ablated within the same procedure. Follow-up (FU) visits were performed after 1, 3, 6 and 12 months with 12-lead-ECG, 24h-Holter-ECG and 4-days-Holter ECG. Mean FU was 11 ± 7 months with 1.1 interventions per patient (24 redo cases). During FU, 122 of 181 patients with paroxysmal AF (69%) and 23 of 40 patients with persistant AF (58%) were in stable sinus rhythm (SR) after ablation. 159 (62.8%) patients wer under antiarrhythmic drugs after ablation, 214 (84.5%) patients with additional β-blockers. Total procedure time was 71 ± 19 min, and total fluoroscopy time was 16 ± 6 min. In 3 cases (1.2%) procedure-related complications occured. Pulmonary vein isolation by using the PVAC-ablation catheter is a safe and effective method in treatment of paroxysmal and persistant AF.

Differential effectiveness of pharmacological strategies to reveal dormant pulmonary vein conduction: a clinical-experimental correlation

BACKGROUND

Atrial fibrillation recurs in ∼30%-40% of patients after pulmonary vein (PV) isolation (PVI) procedures, often because of restored PV-left atrial (LA) conduction. Adenosine or isoproterenol are used clinically to reveal dormant PV conduction and guide additional ablation.

OBJECTIVE

The purpose of this study was to assess the differential efficacy of adenosine and/or isoproterenol in revealing dormant PV conduction.

METHODS

In 25 patients undergoing PVI, dormant conduction was assessed sequentially in response to intravenous adenosine, isoproterenol, and adenosine plus isoproterenol in 100 PVs. To study mechanisms, PVs were isolated by radiofrequency ablation in coronary-perfused canine LA-PV preparations. After PVI, resting membrane potential from PV cells was recorded before and after 1 mM adenosine, 1 μM isoproterenol, 1 μM isoproterenol plus 1 mM adenosine, or no drug (controls).

RESULTS

Clinical PVI was successful in all 100 PVs, with dormant conduction in 31. Sensitivity for dormant conduction was isoproterenol 10%; adenosine 87% (P <.001 vs. isoproterenol); and isoproterenol + adenosine 100% (P = .13 vs. adenosine). Dormant PV conduction in vitro was revealed with adenosine (53%) and adenosine + isoproterenol (60%) but not with isoproterenol alone or in controls (P <.01). Radiofrequency lesions producing PVI depolarized resting membrane potential, causing inexcitability. Postablation, resting membrane potential hyperpolarized after both adenosine and isoproterenol, but adenosine-induced changes were greater (9.1 ± 0.6 mV, vs. 3.8 ± 0.6 mV; P <0.001), with no significant additional effect when isoproterenol was added to adenosine.

CONCLUSION

Adenosine is superior to isoproterenol in revealing dormant PVs clinically and experimentally because of more effective adenosine-induced hyperpolarization. Adding isoproterenol to adenosine had no significant additional value.

Left atrial reservoir function predicts atrial fibrillation recurrence after catheter ablation: a two-dimensional speckle strain study

BACKGROUND

Predictors of atrial fibrillation (AF) recurrence after catheter ablation (CA) are not fully defined. We hypothesized that 2D left atrial (LA) regional strain maps would help identify abnormal atrial substrate that increases susceptibility to AF recurrence post-CA.

METHODS AND RESULTS

Sixty-three patients (63 ± 10 years, 60% male) underwent CA for symptomatic paroxysmal (75%) or persistent (25%) AF. Baseline LA mechanical function determined using speckle tracking echocardiography was compared between those with AF recurrence (AFR) and no recurrence post-CA. Bi-dimensional global and regional maps of LA wall velocity, strain, and strain rate (SR) were obtained during end ejection and early diastole. After 18 ± 12 months of follow-up, 34 patients were free of AFR post-CA. There were no differences in clinical characteristics, LA and LV volumes, and Doppler estimates of LV diastolic function and filling pressures at baseline between patients with recurrent AF and those that maintained sinus rhythm. However, the LA emptying fraction (55 ± 17% vs. 64 ± 14%, p = 0.04), global and regional systolic and diastolic strains, SR, and velocities were reduced in patients with recurrent AF. There was marked attenuation of peak LA lateral wall longitudinal strain (LS; 11 ± 7% vs. 20 ± 14%, p = 0.007) and SR (0.9 ± 0.4 vs.1.3 ± 0.6 s(-1), p = 0.01). Multivariate analysis revealed lateral wall LS (odds ratio = 1.15, 95% CI = 1.02-1.28, p = 0.01) as an independent predictor of AFR.

CONCLUSIONS

Regional LA lateral wall LS is a pre-procedural determinant of AFR in patients undergoing CA, independent of LA enlargement. Characterization of atrial myocardial tissue properties by speckle tracking echo may aid the appropriate selection of adjunctive strategies and prognostication of patients undergoing CA.

Catheter ablation of atrial fibrillation as first-line therapy--a single-centre experience

AIMS

The aims of the study were (i) to assess the characteristics of patients selected for atrial fibrillation (AF) ablation as first-line therapy, (ii) to identify current clinical criteria for such a strategy, and (iii) to analyse the outcome compared with patients who had failure of antiarrhythmic drug (AAD) therapy prior to ablation.

METHODS AND RESULTS

Consecutive patients undergoing ablation of AF were included in a prospective registry. Serial long-term electrocardiogram monitoring and clinical follow-up were performed after 3, 6, and 12 months. Out of 434 patients, 17% underwent AF catheter ablation as first-line therapy (AAD-), and 83% had undergone at least one AAD trial (AAD+). In AAD- patients, the reasons for this strategy were: (i) patient preference, n= 51 (71%); (ii) contra-indication to AAD, n= 21 (29%). Atrial fibrillation duration prior to ablation was shorter (52 ± 54 vs. 78 ± 81 months, P= 0.005), and the percentage of patients hospitalized for AF (32% vs. 48%, P= 0.01) was lower in AAD- patients. Long-term multiple procedure success rate (78% vs. 64%, P= 0.03) was higher in the AAD- group, and there were less repeat ablations in this group (21% vs. 38%, P= 0.01).

CONCLUSION

Catheter ablation was first-line therapy of AF in a significant number of patients, according either to patient preference or to medical factors, and this had important implications. Ablative therapy was performed at an earlier stage of the disease, and was associated with a significantly higher success rate and with a decreased need for repeat procedures.

New drugs vs. old concepts: a fresh look at antiarrhythmics

Common arrhythmias, particularly atrial fibrillation (AF) and ventricular tachycardia/fibrillation (VT/VF) are a major public health concern. Classic antiarrhythmic (AA) drugs for AF are of limited effectiveness, and pose the risk of life-threatening VT/VF. For VT/VF, implantable cardiac defibrillators appear to be the unique, yet unsatisfactory, solution. Very few AA drugs have been successful in the last few decades, due to safety concerns or limited benefits in comparison to existing therapy. The Vaughan-Williams classification (one drug for one molecular target) appears too restrictive in light of current knowledge of molecular and cellular mechanisms. New AA drugs such as atrial-specific and/or multichannel blockers, upstream therapy and anti-remodeling drugs, are emerging. We focus on the cellular mechanisms related to abnormal Na⁺ and Ca²⁺ handling in AF, heart failure, and inherited arrhythmias, and on novel strategies aimed at normalizing ionic homeostasis. Drugs that prevent excessive Na⁺ entry (ranolazine) and aberrant diastolic Ca²⁺ release via the ryanodine receptor RyR2 (rycals, dantrolene, and flecainide) exhibit very interesting antiarrhythmic properties. These drugs act by normalizing, rather than blocking, channel activity. Ranolazine preferentially blocks abnormal persistent (vs. normal peak) Na⁺ currents, with minimal effects on normal channel function (cell excitability, and conduction). A similar "normalization" concept also applies to RyR2 stabilizers, which only prevent aberrant opening and diastolic Ca²⁺ leakage in diseased tissues, with no effect on normal function during systole. The different mechanisms of action of AA drugs may increase the therapeutic options available for the safe treatment of arrhythmias in a wide variety of pathophysiological situations.

Current ablation strategies for persistent and long-standing persistent atrial fibrillation

Atrial fibrillation (AF) is associated with an increased risk of cardiac and overall mortality. Restoration and maintenance of sinus rhythm is of paramount importance if it can be accomplished without the use of antiarrhythmic drugs. Catheter ablation has evolved into a well-established treatment option for patients with symptomatic, drug-refractory AF. Ablation strategies which target the pulmonary veins are the cornerstone of AF ablation procedures, irrespective of the AF type. Ablation strategies in the setting of persistent and long-standing persistent AF are more complex. Many centers follow a stepwise ablation approach including pulmonary vein antral isolation as the initial step, electrogram-based ablation at sites exhibiting complex fractionated atrial electrograms, and linear lesions. Up to now, no single strategy is uniformly effective in patients with persistent and long-standing persistent AF. The present study reviewed the efficacy of the current ablation strategies for persistent and long-standing persistent AF.

Cost of AF Ablation: Where Do We Stand?

Atrial fibrillation (AF) is a common and frequently disabling chronic condition associated with significant patient morbidity and affecting an increasing stratum of our ageing society. Direct costs related to atrial fibrillation are comprised from direct cost of medical therapy, catheter ablation, and related hospitalizations and imaging procedures, with indirect costs related to complications of the primary therapeutic strategy, management of related conditions, as well as disability and loss in quality of life related to AF. Over the last decade, catheter ablation became a promising alternative to rate and rhythm control among symptomatic AF patients. The purpose of this paper is to describe the evidence on the financial implications related to ablation based on published data and authors' experience.

Review of contemporary antiarrhythmic drug therapy for maintenance of sinus rhythm in atrial fibrillation

Atrial fibrillation (AF) is the most common rhythm disturbance seen in clinical practice, and its prevalence and incidence are rising rapidly as the population ages with its attendant complications. Management of AF involves anticoagulation, and fortunately new drugs for long-term anticoagulation are now available. Maintenance of sinus rhythm, though intuitively better than rate control strategy, has not been shown to offer mortality benefit. Still, maintenance of sinus rhythm is considered an appropriate therapeutic strategy when symptoms are not adequately controlled with rate control. Though significant advances have been made in ablation techniques for AF, pharmacological therapy is still the first line of treatment for rate control and maintenance of sinus rhythm, given ease of use, noninvasive nature, and limited experience with catheter-based ablation techniques. Class IC and III agents (Vaughan Williams classification) form the backbone for pharmacological maintenance of sinus rhythm. Dronedarone, a recently approved class III agent, provides a significant advance because of its relatively safe side effect profile. Currently drugs with selective atrial channels blocking properties, like Vernakalant, are being tested in trials and may provide an opportunity to maintain sinus rhythm with limited toxicity. Large trials are also being conducted to better define the efficacy of catheter-based ablation strategy as first-line treatment. Here, we review the current status of commonly used antiarrhythmic medications for the maintenance of sinus rhythm in AF.

Atrial fibrillation: pathophysiology and current therapy

Atrial fibrillation is a common cardiac arrhythmia with rapid and irregular atrial activity. Instead of uniformly contracting as one chamber, the atrial compartment fibrillates. Several studies have demonstrated that this arrhythmia contributes substantially to cardiac morbidity and mortality. The purpose of this review is to describe the pathophysiology and clinical management of this arrhythmia.

Improvements in symptoms and quality of life in patients with paroxysmal atrial fibrillation treated with radiofrequency catheter ablation versus antiarrhythmic drugs

BACKGROUND

In patients with paroxysmal atrial fibrillation (AF), catheter ablation maintains sinus rhythm more effectively than antiarrhythmic drugs (AADs), but its effect on symptoms and quality of life (QOL) has not been fully characterized.

METHODS AND RESULTS

We evaluated symptoms and QOL in a multicenter, randomized trial comparing catheter ablation with AADs as second-line treatment for patients with paroxysmal AF. The Short Form (SF)-36 health survey and the AF Symptom Checklist were administered at baseline and 3, 6, and 9 months after a blanking or dose-titration period. The primary between-group comparisons were conducted at 3 months because of permitted crossover from AAD to ablation beyond this time. Additional analyses based on subsequent follow-up were performed, including the construction of mixed linear regression models to assess the impact of multiple factors on follow-up QOL scores. At baseline in both the ablation (n=103) and the AAD (n=56) groups, 7 of 8 SF-36 scales were well below population norms, as were the physical (PCS) and mental (MCS) summary scores. At 3 months, the same 7 SF-36 scales were significantly (P<0.01) higher in the ablation than in the AAD group, as were the PCS (52.0±7.8 versus 47.1±10.6; P<0.01) and MCS (52.4±8.1 versus 46.6±9.8; P<0.01) scores, whereas symptom frequency (9.3±9.2 versus 19.0±12.6; P<0.001) and symptom severity (7.7±7.2 versus 16.2±10.0; P<0.001) were significantly reduced. In multivariable analysis, ablation and recurrent arrhythmias most strongly correlated with QOL changes over time.

CONCLUSIONS

For second-line therapy of paroxysmal AF, ablation is superior to AAD treatment at improving symptoms and QOL.

CLINICAL TRIAL REGISTRATION

URL: http://www.clinicaltrials.gov. Unique identifier: NCT00116428.

Meta-analysis of the effectiveness and safety of catheter ablation of atrial fibrillation in patients with versus without left ventricular systolic dysfunction

Catheter ablation is a promising therapy for atrial fibrillation (AF), but its utility in patients with left ventricular systolic dysfunction (LVSD) is uncertain. The objectives of this study were to perform a systematic review and meta-analysis of randomized and observational studies comparing the rates of recurrent AF, atrial tachycardia (AT), and complications after AF catheter ablation in those with versus without LVSD and to summarize the impact of catheter ablation on the left ventricular ejection fraction. Seven observational studies and 1 randomized trial were included (total n = 1,851). Follow-up ranged from 6 to 27 months. In those with LVSD, 28% to 55% were free of AF or AT on follow-up after 1 AF catheter ablation, increasing to 64% to 96% after a mean of 1.4 procedures. The relative risk for recurrent AF or AT in those with versus without LVSD was 1.5 (95% confidence interval 1.2 to 1.8, p <0.001) after 1 procedure and 1.2 (95% confidence interval 0.9 to 1.5, p = 0.2) after multiple procedures. No difference in complications was observed in patients with (3.5%) versus without (2.5%) heart failure (p = 0.55). After catheter ablation, those with LVSD experienced a pooled absolute improvement in the left ventricular ejection fraction of 0.11 (95% confidence interval 0.07 to 0.14, p <0.001). In conclusion, patients with and without LVSD had similar risk for recurrent AF or AT after catheter ablation, but repeat procedures were required more often in those with LVSD. Significant improvements in left ventricular ejection fractions after ablation were observed in those with LVSD. Randomized trials are needed given the limitations of present data.

Atrial fibrillation-the final frontier

Atrial fibrillation (AF) is the most common sustained cardiac arrhythmia and represents a significant health care issue. The diagnosis and management of AF uses a significant proportion of the health care budget and is responsible for substantial morbidity and mortality. Restoration and maintenance of sinus rhythm is still an important treatment option for symptomatic AF. Anti-arrhythmic drugs (AADs) have had inconsistent results for the prevention of recurrent AF and have been hampered by significant adverse effects. Catheter ablation has rapidly evolved and is fast becoming an alternative for AF prevention. Although multiple treatment options exist, no single modality is effective for all patients. This review outlines best current practice for AF prevention and future perspectives, focusing on new and promising developments in antiarrhythmic drug therapy, strategies for ablation therapy, and forms of hybrid therapy that may offer improved outcomes in selected patients.

Developing the Safety of Atrial Fibrillation Ablation Registry Initiative (SAFARI) as a collaborative pan-stakeholder critical path registry model: a Cardiac Safety Research Consortium "Incubator" Think Tank

Although several randomized clinical trials have demonstrated the safety and efficacy of catheter ablation of atrial fibrillation (AF) in experienced centers, the outcomes of this procedure in routine clinical practice and in patients with persistent and long-standing persistent AF remain uncertain. Brisk adoption of this therapy by physicians with diverse training and experience highlights potential concerns regarding the safety and effectiveness of this procedure. Some of these concerns could be addressed by a national registry of AF ablation procedures such as the Safety of Atrial Fibrillation Ablation Registry Initiative that was initially proposed at a Cardiac Safety Research Consortium Think Tank meeting in April 2009. In January 2010, the Cardiac Safety Research Consortium, in collaboration with the Duke Clinical Research Institute, the US Food and Drug Administration, the American College of Cardiology, and the Heart Rhythm Society, held a follow-up meeting of experts in the field to review the construct and progress to date. Other participants included the National Heart, Lung, and Blood Institute; the Centers for Medicare and Medicaid Services; the Agency for Healthcare Research and Quality; the AdvaMed AF working group; and additional industry representatives. This article summarizes the discussions that occurred at the meeting of the state of the Safety of Atrial Fibrillation Ablation Registry Initiative, the identification of a clear pathway for its implementation, and the exploration of solutions to potential issues in the execution of this registry.

Is AF Ablation Cost Effective?

The use of catheter ablation to treat AF is increasing rapidly, but there is presently an incomplete understanding of its cost-effectiveness. AF ablation procedures involve significant up-front expenditures, but multiple randomized trials have demonstrated that ablation is more effective than antiarrhythmic drugs at maintaining sinus rhythm in a second-line and possibly first-line rhythm control setting. Although truly long-term data are limited, ablation, as compared with antiarrrhythmic drugs, also appears associated with improved symptoms and quality of life and a reduction in downstream hospitalization and other health care resource utilization. Several groups have developed cost effectiveness models comparing AF ablation primarily to antiarrhythmic drugs and the model results suggest that ablation likely falls within the range generally accepted as cost-effective in developed nations. This paper will review available information on the cost-effectiveness of catheter ablation for the treatment of atrial fibrillation, and discuss continued areas of uncertainty where further research is required.

Is catheter ablation a mature fruit for treatment of atrial fibrillation?--is catheter ablation established as a treatment optionof atrial fibrillation? (Con)

In recent years, catheter ablation for atrial fibrillation (AF) has evolved in tandem with the results from many large-scale randomized clinical studies with antiarrhythmic drugs. The current situations seem to be a concerted move from pharmacological to non-pharmacological treatment. However, the clinical studies with medications have revealed an important viewpoint for the management of AF: the importance of the core aim of AF treatment and the position of electrographic findings as a surrogate marker. Catheter ablation is under challenge as the answers to these issues are awaited. Moreover, many problems with this invasive therapy are to be solved, most of them deriving from the vague definition of success of ablation and no standardization of the technique. For these reasons, catheter ablation is still on the way to maturation and multicenter studies in Japan are required to set a fair benchmark for Japanese patients, drawing a lesson from randomized clinical studies with medications.

Catheter ablation is established as a treatment option for atrial fibrillation--is catheter ablation established as a treatment option of atrial fibrillation? (Pro)

Atrial fibrillation (AF) is the most common arrhythmia in clinical practice and it has a significant impact on morbidity and mortality. Large randomized trials have failed to demonstrate a benefit for mortality of the pharmacological rhythm control strategy as compared with the rate control strategy, indicating that rate control may be an adequate treatment for AF. However, further study determined that the presence of AF at the time of study termination was a more potent predictor of mortality than the treatment strategy, suggesting the importance of sinus rhythm. On the other hand, catheter ablation recently has emerged as an alternative treatment option to pharmacological therapy for AF. Although AF ablation is an invasive strategy, over the past decade its efficacy has increased and the complication rate has decreased with the growing experience of operators and evolving technology. Moreover, the ablation methodology, such as pulmonary vein isolation based ablation, is consistent worldwide and the success rate of AF ablation, especially in paroxysmal AF, is similar. Therefore, catheter ablation is established as a treatment option for AF.

Comparison of rhythm restoration strategies in paroxysmal atrial fibrillation

Evaluation of: Wilber DJ, Pappone C, Neuzil P et al.; ThermoCool AF Trial Investigators. Comparison of antiarrhythmic drug therapy and radiofrequency catheter ablation in patients with paroxysmal atrial fibrillation: a randomized controlled trial. JAMA 303(4), 333-340 (2010). Atrial fibrillation is the most common cardiac arrhythmia and is responsible for the highest number of cardioembolic strokes worldwide. Discovery of the role of pulmonary veins as a trigger has been an important breakthrough that has led to the development of catheter ablation, an established curative therapy for drug-resistant atrial fibrillation. In a systematically conducted prospective, multicenter, randomized trial comparing pulmonary vein isolation-based catheter ablation with pharmacological rhythm control, the currently recommended first-line therapy in atrial fibrillation, catheter ablation, proved superior to antiarrhythmic drugs with regards to the maintenance of sinus rhythm and improvement in symptoms and quality of life at 1 year of follow-up, with comparable adverse event rates. Early use of catheter ablation in selected patients with paroxysmal atrial fibrillation unresponsive to one antiarrhythmic drug is promising.

[Psychosomatic aspects of cardiac arrhythmias]

Emotional stress facilitates the occurrence of cardiac arrhythmias including sudden cardiac death. The prevalence of anxiety and depression is increased in cardiac patients as compared to the normal population. The risk of cardiovascular mortality is enhanced in patients suffering from depression. Comorbid anxiety disorders worsen the course of cardiac arrhythmias. Disturbance of neurocardiac regulation with predominance of the sympathetic tone is hypothesized to be causative for this. The emotional reaction to cardiac arrhythmias is differing to a large extent between individuals. Emotional stress may result from coping with treatment of cardiac arrhythmias. Emotional stress and cardiac arrhythmias may influence each other in the sense of a vicious circle. Somatoform cardiac arrhythmias are predominantly of psychogenic origin. Instrumental measures and frequent contacts between physicians and patients may facilitate disease chronification. The present review is dealing with the multifaceted relationships between cardiac arrhythmias and emotional stress. The underlying mechanisms and corresponding treatment modalities are discussed.

Radiofrequency catheter ablation for atrial fibrillation

Radiofrequency catheter ablation can lead to improvements in morbidity and mortality rates and quality of life for individuals with atrial fibrillation.