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

Health Outcomes With Catheter Ablation or Antiarrhythmic Drug Therapy in Atrial Fibrillation

Background—

Patients with atrial fibrillation (AF) face significant risks of stroke and heart failure. The objective of this study was to determine whether AF ablation reduces the long-term risk of stroke or heart failure compared with antiarrhythmic drug therapy.

Methods and Results—

A coding algorithm was used to identify AF patients treated with catheter ablation (n=3194) or antiarrhythmic drugs without ablation (n=6028) between 2005 and 2009 using The MarketScan Research Database from Thomson Reuters From this sample, 801 pairs were propensity matched, based on 15 demographic and clinical characteristics and baseline medication use. Rates of stroke/transient ischemic attack (TIA) and heart failure hospitalizations for up to 3 years were examined. Patients treated with catheter ablation had a significantly lower rate of stroke or TIA (3.4% per year) than a group of patients with AF managed with antiarrhythmic drugs only (5.5% per year), with an unadjusted hazard ratio of 0.62 (95% CI, 0.44–0.86; P =0.005). The rates for heart failure hospitalization were 1.5% per year in the ablation group and 2.2% per year in the antiarrhythmic drug group, with an unadjusted hazard ratio of 0.69 (95% CI, 0.42–1.15; P =0.158). These results were minimally altered in Cox proportional hazards models, which further adjusted for potential confounders not well balanced by the propensity matching.

Conclusions—

In a large propensity-matched community sample, AF ablation was associated with a reduced risk of stroke/TIA and no significant difference in heart failure hospitalizations compared with antiarrhythmic drug therapy. These findings require confirmation with randomized study designs.

The potential utility of (123)I-mIBG in atrial fibrillation and in the electrophysiology laboratory

A novel indication for (123)I-mIBG has recently been proposed to risk stratify patients with atrial fibrillation. This review puts into perspective the utility and importance of such a risk stratification modality, in the setting of the epidemic of atrial fibrillation, which also relates to the prevalence of heart failure, obesity, hypertension, and stroke. The authors argue that the epic cost of care for patients with paroxysmal and more advanced forms of atrial fibrillation-including catheter ablation, heart failure, and stroke management-coupled with the poor efficacy of all treatment modalities in advanced atrial fibrillation, make necessary a paradigm shift where only paroxysmal atrial fibrillation that demonstrably will turn into permanent fibrillation should be targeted aggressively. If this premise is accepted, then (123)I-mIBG nuclear imaging for risk stratification becomes a vital tool for the care of the individual patient, as well as for disease control and cost containment in the population, since (123)I-mIBG scanning alone can predict (with hazard ratios of the order of 3.0-5.0) the future occurrence of permanent atrial fibrillation or heart failure.

Atrial fibrillation

The management of atrial fibrillation has evolved greatly in the past few years, and many areas have had substantial advances or developments. Recognition of the limitations of aspirin and the availability of new oral anticoagulant drugs that overcome the inherent drawbacks associated with warfarin will enable widespread application of effective thromboprophylaxis with oral anticoagulants. The emphasis on stroke risk stratification has shifted towards identification of so-called truly low-risk patients with atrial fibrillation who do not need antithrombotic therapy, whereas oral anticoagulation therapy should be considered in patients with one or more risk factors for stroke. New antiarrhythmic drugs, such as dronedarone and vernakalant, have provided some additional opportunities for rhythm control in atrial fibrillation. However, the management of the disorder is increasingly driven by symptoms. The availability of non-pharmacological approaches, such as ablation, has allowed additional options for the management of atrial fibrillation in patients who are unsuitable for or intolerant of drug approaches.

Advancing cardiovascular research

Over the past 50 years, we have seen dramatic changes in cardiovascular science and clinical care, accompanied by marked declines in the morbidity and mortality. Nonetheless, cardiovascular disease remains the leading cause of death and disability in the world, and its nature is changing as Americans become older, fatter, and ethnically more diverse. Instead of young or middle-aged men with ST-segment elevation myocardial infarction, the "typical" cardiac patient now presents with acute coronary syndrome or with complications related to chronic hypertension or ischemic heart disease, including heart failure, sudden death, and atrial fibrillation. Analogously, structural heart disease is now dominated by degenerative valve or congenital disease, far more common than rheumatic disease. The changing clinical scene presents cardiovascular scientists with a number of opportunities and challenges, including taking advantage of high-throughput technologies to elucidate complex disease mechanisms, accelerating development and implementation of evidence-based strategies, assessing evolving technologies of unclear value, addressing a global epidemic of cardiovascular disease, and maintaining high levels of innovation in a time of budgetary constraint and economic turmoil.

Update on the clinical management of atrial fibrillation: guidelines and beyond

In clinical practice, atrial fibrillation (AF) is the most commonly encountered arrhythmia. With the aging of the US population, the number of patients with AF that physicians encounter will increase. Atrial fibrillation management involves a combination of rate- and rhythm-control strategies with thromboprophylaxis, a complicated endeavor given side effect profiles of treatments, patient comorbidities, and anticoagulation treatment requirements. Early treatment discontinuation and poor compliance with anticoagulation treatment are frequent and result in increased mortality, a 5-fold increased risk of ischemic stroke, decreased health-related quality of life, and decreased exercise capacity. In 2006, the American College of Cardiology/American Heart Association/European Society of Cardiology (ACC/AHA/ESC) provided guidelines for the management of patients with AF. Recently, the ACC Foundation, AHA, and Heart Rhythm Society released updates to these guidelines (January and February 2011). This article aims to assist physicians in improving the management of patients with AF by focusing on the main components of therapy as reflected in the guidelines, and by providing an update on new US Food and Drug Administration-approved treatments.

Left Atrial Catheter Ablation and Ischemic Stroke

Left atrial catheter ablation (LACA) has become an established therapy to abolish drug-refractory symptomatic paroxysmal and persistent atrial fibrillation. Restoring sinus rhythm by LACA may help to prevent atrial fibrillation-related strokes, but presently there is no evidence from randomized clinical trials to support this notion. This review summarizes the current knowledge and uncertainties regarding LACA and procedure-related ischemic stroke. In fact, most patients who undergo LACA have a rather low annual stroke risk even when left untreated, whereas LACA imposes a risk of procedure-related stroke of ≈0.5% to 1%. In addition, LACA may cause cerebral microemboli, resulting in ischemic lesions. These cerebral lesions, detectable by high-resolution MRI, could contribute to neuropsychological deficits and cognitive dysfunction. Furthermore, recurrent atrial fibrillaton episodes can be detected up to years after LACA and might cause ischemic strokes, especially in those patients in whom therapeutic anticoagulation was discontinued. Further prospective multicenter trials are needed to identify procedure-dependent risk factors for stroke and to optimize postprocedural anticoagulation management.

Cryoballoon in AF ablation: impact of PV ovality on AF recurrence

INTRODUCTION

Complete occlusion of the pulmonary veins (PV) is crucial for successful PV isolation. While two different sizes of cryoballoons (23 and 28 mm) are available, complete occlusion is not always achieved in any given PV. We investigated the role of PV ostial anatomy during cryoballoon PV occlusion grading and atrial fibrillation (AF) recurrence rate.

METHODS

PV ostial diameter was analyzed in 168 consecutive patients (111 men, 61 ± 10 years, 124 paroxysmal (px) and 44 persistent AF) using cardiac computed tomography (CT) prior to procedure. The ovality index at the PV ostial level was calculated in any given PV. During follow-up, 7-day holter monitors were performed at 1, 3, 6, 9, 12, 18 and 24 months post-ablation.

RESULTS

The success rate at 12 ± 6 months follow-up was 69% including a 3-month blanking period (px AF: 66%; persistent AF 77%). The ovality index of the left-sided PVs was significantly larger ("more oval") than that of the right-sided PVs (p<0.001). An optimized PV occlusion in all individual PVs (complete occlusion, grading 4/4) was achieved during ablation in 49% of patients with AF recurrence and in 73% of patients without AF recurrence (p=0.004). Patients with AF recurrence had "more oval" left-sided PVs compared to patients free from AF recurrence (LSPV 0.40 ± 0.2 vs. 0.33 ± 0.2; p=0.04 and LIPV 0.41 ± 0.3 vs. 0.32 ± 0.2; p=0.03), whereas no significant association was found for right sided PVs.

CONCLUSION

The ostial PV anatomy seems to have an important impact on clinical outcome and should be considered when planning and performing cryoballoon AF ablation procedures.

Cardiovascular outcomes in the AFFIRM Trial (Atrial Fibrillation Follow-Up Investigation of Rhythm Management). An assessment of individual antiarrhythmic drug therapies compared with rate control with propensity score-matched analyses

OBJECTIVES

The impact of individual antiarrhythmic drugs (AADs) on mortality and hospital stay in atrial fibrillation (AF) was evaluated.

BACKGROUND

Cardiovascular (CV) outcomes in AF patients receiving pharmacologic rhythm control therapy have not been compared with rate control therapy on the basis of AAD selection.

METHODS

We compared CV outcomes in the AFFIRM (Atrial Fibrillation Follow-Up Investigation of Rhythm Management) trial in subgroups defined by the initial AAD selected with propensity score matched subgroups from the rate arm (Rate).

RESULTS

Seven hundred twenty-nine amiodarone patients, 606 sotalol patients, and 268 Class 1C patients were matched. The composite outcome of mortality or cardiovascular hospital stays (CVH) showed better outcomes with Rate compared with amiodarone (hazard ratio [HR]: 1.18, 95% confidence interval [CI]: 1.03 to 1.36, p = 0.02), sotalol (HR: 1.32, 95% CI: 1.13 to 1.54, p < 0.001), and Class 1C (HR: 1.22, 95% CI: 0.97 to 1.56, p = 0.10). There was a nonsignificant increase in mortality with amiodarone (HR: 1.20, 95% CI: 0.94 to 1.53, p = 0.15) with the risk of non-CV death being significantly higher with amiodarone versus Rate (HR: 1.11, 95% CI: 1.01 to 1.24, p = 0.04). First CVH event rates at 3 years were 47% for amiodarone, 50% for sotalol, and 44% for Class 1C versus 40%, 40%, and 36%, respectively, for Rate (amiodarone HR: 1.20, 95% CI: 1.03 to 1.40, p = 0.02, sotalol HR: 1.364, 95% CI: 1.16 to 1.611, p < 0.001, Class 1C HR: 1.24, 95% CI: 0.96 to 1.60, p = 0.09). Time to CVH with intensive care unit stay or death was shorter with amiodarone (HR: 1.22, 95% CI: 1.02 to 1.46, p = 0.03).

CONCLUSIONS

In AFFIRM, composite mortality and CVH outcomes differed for Rate and AADs due to differences in CVH; CVH event rates during follow-up were high for all cohorts, but they were higher for all groups on AADs. Death, intensive care unit hospital stay, and non-CV death were more frequent with amiodarone.

Radiofrequency catheter ablation and antiarrhythmic drug therapy: a prospective, randomized, 4-year follow-up trial: the APAF study

BACKGROUND

Information on comparative outcome between radiofrequency catheter ablation (RFA) and antiarrhythmic drugs (AADs) >1 year after randomization is important for clinical decision-making.

METHODS AND RESULTS

A total of 198 patients (age, 56 ± 10 years) with paroxysmal atrial fibrillation were randomly assigned to RFA (99 patients) or to AADs (99 patients). We evaluated efficacy of RFA or AADs in a comparable 48-month follow-up period according to intention-to-treat analysis. Cardiac rhythm was assessed with daily transtelephonic transmissions. Quality of life was also analyzed. At 4 years, among the 99 patients first assigned to RFA, the procedure was repeated because of recurrent atrial fibrillation/atrial tachycardia in 27 patients (27.3%). Among the 99 patients randomly assigned to AADs, 87 (87.9%) crossed over to undergo RFA and 4 years after random assignment only 12 (12.1%) were in sinus rhythm with AAD alone without ablation. Despite the high level of crossovers, at 4 years the intention-to-treat analysis showed that 72.7% of patients in the ablation arm and 56.5% of those initially randomly assigned to AADs were free of recurrent atrial fibrillation/atrial tachycardia (P=0.017). During the follow-up, 19.2% of AAD patients progressed to persistent atrial fibrillation before switching to RFA. RFA significantly improved quality of life (P<0.001), whereas before crossing over to RFA, patients receiving AADs showed poorer quality of life. Except for new left atrial tachycardia, there were no serious complications caused by RFA.

CONCLUSIONS

With follow-up extended to 4 years after randomly assigned, ablation remains superior to antiarrhythmic drug in these patients with paroxysmal atrial fibrillation.

CLINICAL TRIAL REGISTRATION

URL: http://www.clinicaltrials.gov. Unique identifier: NCT00340314.

New technologies for catheter ablation of atrial fibrillation

OPINION STATEMENT

The past decade of ablation for atrial fibrillation (AF) has seen the adaptation of catheters designed for "focal" tachycardias or single pathways to perform wide encirclement of the pulmonary veins (PV). During the next decade, technologies designed specifically for PV isolation will emerge. Each system has its unique attributes. The cryoballoon system offers rapid PV isolation and the promise of enhanced safety, whereas the success rate is likely to be similar to catheter-based approaches. Although preclinical studies do suggest a very low likelihood of left atria-esophageal fistula using this technology, concerns of phrenic nerve damage and a small incidence of PV stenosis need to be addressed. It is likely that use of the larger 28-mm balloon will mitigate these concerns. The cryoballoon is also the first balloon technology to be approved by the US Food and Drug Administration for clinical use, and this may gain the technology an early foothold in the AF ablation market. The laser balloon ablation system is a more time-consuming and technically demanding procedure, and the risk of thrombus formation if ablation is performed in stagnant blood is a concern. However, early studies suggest a high rate of persistent PV isolation, which hopefully will translate into high single-procedure efficacy. The Ablation Frontiers system is the only system currently being developed for more persistent forms of AF. This system offers a rapid approach to PV isolation and left atrial defragmentation. The early results do not demonstrate a success rate better than that described for catheter ablation; however, the results are difficult to compare to standard catheter ablation in this recalcitrant patient group without a prospective randomized study.

Rationale and current perspective for early rhythm control therapy in atrial fibrillation

Atrial fibrillation (AF) is the most common sustained arrhythmia and an important source for mortality and morbidity on a population level. Despite the clear association between AF and death, stroke, and other cardiovascular events, there is no evidence that rhythm control treatment improves outcome in AF patients. The poor outcome of rhythm control relates to the severity of the atrial substrate for AF not only due to the underlying atrial remodelling process but also due to the poor efficacy and adverse events of the currently available ion-channel antiarrhythmic drugs and ablation techniques. Data suggest, however, an association between sinus rhythm maintenance and improved survival. Hypothetically, sinus rhythm may also lead to a lower risk of stroke and heart failure. The presence of AF, thus, seems one of the modifiable factors associated with death and cardiovascular morbidity in AF patients. Patients with a short history of AF and the underlying heart disease have not been studied before. It is fair to assume that abolishment of AF in these patients is more successful and possibly also safer, which could translate into a prognostic benefit of early rhythm control therapy. Several trials are now investigating whether aggressive early rhythm control therapy can reduce cardiovascular morbidity and mortality and increase maintenance of sinus rhythm. In the present paper we describe the background of these studies and provide some information on their design.

Antiarrhythmic drugs for maintaining of sinus rhythm

The pharmacological strategy to treat atrial fibrillation (AF) has been studied in the last years by a number of randomized studies. The overall results showed that the rhythm control strategy is not superior to the rate control strategy in terms of mortality or stroke, mostly due to limited efficacy and toxicity of antiarrhyhtmic drugs in the rhythm control patients. Regarding to these data, current antiarrhythmic therapy for recurrent AF is recommended on the basis of choosing safer, although possibly less efficacious drug. Flecainide, propafenone, sotalol and dronedarone are the first-line drugs for patients with a minimal or no heart disease, or hypertension without left ventricular hypertrophy. Sotalol and dronedarone are recommended as first-line drugs for patients with a coronary artery disease. Dronedarone should be considered in order to reduce cardiovascular hospitalizations related to AF/flutter. It can also be used safely in patients with hypertensive heart disease and stable NYHA class I-II heart failure. Amiodarone is the most effective antiarrhythmic in all clinical settings, but because of its toxicity profile should generally be used when other agents have failed or are contraindicated. Amiodarone is recommended as drug of choice in patients with severe heart failure or recently unstable NYHA class II.

New directions in clinical outcomes assessment : VIth International Symposium on Interventional Electrophysiology in the Management of Cardiac Arrhythmias

In recent years, electrophysiology clinical research has made tremendous progress. Not only have the standards for conducting research and assessing clinical outcomes improved substantially, but the power of well-conducted and designed randomized clinical trials has been realized. This has led to the emergence of a plethora of randomized clinical trials in electrophysiology. Despite these improvements, there is an immense need to explore and develop better approaches for assessing clinical outcomes. In this article, I review the strengths, challenges, and limitations of randomized clinical trials, especially as they relate to the field of electrophysiology. To address some of these challenges, I propose potential solutions that involve enhancing clinical trials and complementing them with large registries and databases of electronic medical records. If prudently developed and executed, these new directions in assessing clinical outcomes have great potential to inform, and thereby improve the care of patients receiving electrophysiologic interventions.

n-3 polyunsaturated fatty acids in the prevention of atrial fibrillation recurrences after electrical cardioversion: a prospective, randomized study

BACKGROUND

n-3 polyunsaturated fatty acids (n-3 PUFAs) exert antiarrhythmic effects and reduce sudden cardiac death. However, their role in the prevention of atrial fibrillation remains controversial. We aimed to determine the effect of n-3 PUFAs in addition to amiodarone and a renin-angiotensin-aldosterone system inhibitor on the maintenance of sinus rhythm after direct current cardioversion in patients with persistent atrial fibrillation.

METHODS AND RESULTS

We conducted a randomized, double-blind, placebo-controlled, parallel-arm trial in patients with persistent atrial fibrillation, with at least 1 relapse after cardioversion, and treated with amiodarone and a renin-angiotensin-aldosterone system inhibitor. Participants were assigned to placebo or n-3 PUFAs 2 g/d and then underwent direct current cardioversion 4 weeks later. The primary end point was the probability of maintenance of sinus rhythm at 1 year after cardioversion. Of 254 screened patients, 199 were found to be eligible and randomized. At the 1-year follow up, the probability of maintenance of sinus rhythm was significantly higher in the n-3 PUFAs-treated patients compared with the placebo group (hazard ratio, 0.62 [95% confidence interval, 0.52 to 0.72] and 0.36 [95% confidence interval, 0.26 to 0.46], respectively; P=0.0001).

CONCLUSIONS

In patients with persistent atrial fibrillation on amiodarone and a renin-angiotensin-aldosterone system inhibitor, the addition of n-3 PUFAs 2 g/d improves the probability of the maintenance of sinus rhythm after direct current cardioversion. Our data suggest that n-3 PUFAs may exert beneficial effects in the prevention of atrial fibrillation recurrence. Further studies are needed to confirm and expand our findings. Clinical Trial Registration- URL: http://www.clinicaltrials.gov. Unique identifier: NCT01198275.

Economic impact to employers of treatment options for cardiac arrhythmias in the US health system

OBJECTIVE

To measure relative employer-sponsored postablation costs for cardiac arrhythmias (CA), specifically atrial fibrillation (AF).

METHODS

Regression-Controlled Employee/Spouse Database study (2001 to 2008) comparing CA patients with and without ablation and AF patients with and without ablation. Regression-adjusted monthly medical, pharmacy, sick leave, and short-term disability costs were calculated 11 months before index to 36 months after index (first ablation date or average date for nonablation patients). Relative pre/postindex comparisons between ablation and nonablation cohorts were calculated and time until ablation procedure cost recovery extrapolated.

RESULTS

Few CA (280 of 11,291; 2.48%) and AF (93 of 3062; 3.04%) patients received ablation. Ablation cohorts cost less than nonablation cohorts postablation. Estimated total ablation-period costs were recovered 38 to 50 months postablation, including employee absence payment recovery within 18 months.

CONCLUSION

Current ablation use in employer-sponsored health plans may improve health care and absence costs over time.

Ablation of Atrial Fibrillation in the Elderly: Current Evidence and Evolving Trends

Management of atrial fibrillation in the elderly presents unique challenges, including deciding upon the best treatment strategy: rate control versus rhythm control. The decision to pursue one treatment strategy over another is based on understanding the underlying disorder: symptomatology from atrial fibrillation itself versus symptoms due to a rapid ventricular response from atrial fibrillation. The ablation strategies for the treatment of atrial fibrillation include atrioventricular junction ablation and pulmonary vein isolation. This review discusses the data on ablation of atrial fibrillation in the elderly, with an emphasis on issues regarding safety and efficacy in this population.

Remote magnetic versus manual catheter navigation for circumferential pulmonary vein ablation in patients with atrial fibrillation

BACKGROUND

Only limited data exist on the clinical utility of remote magnetic navigation (RMN) for pulmonary vein (PV) ablation. Aim of this prospective study was to evaluate the safety and efficacy of RMN for PV isolation as compared to the manual (CON) approach.

METHODS AND RESULTS

A total of 161 consecutive patients undergoing circumferential PV isolation were included. Open-irrigated 3.5 mm ablation catheters under the guidance of a mapping system were used. The catheter was navigated with the Stereotaxis Niobe II system in the RMN group (n = 107) and guided manually in the CON group (n = 54). Electrical isolation of all PVs was achieved in 90% of the patients in the RMN group and in 87% in the CON group (p = 0.6). All subjects were followed every 3 months by 7d Holter-ECG. At 12 months of follow-up, 53.5% (RMN) and 55.5% (CON) of the patients were free of any left atrial tachycardia/atrial fibrillation (AF) episode (p = 0.57). Free of symptomatic AF recurrence were 66.3% (RMN) and 62.1% (CON) of the subjects (p = 0.80). Use of RMN was associated with longer procedure duration (p < 0.0001), ablation times (p < 0.0001), and RF current application duration (p < 0.05). In contrast, fluoroscopy time was lower in the RMN group (p < 0.0001). Major complications occurred in 6 of 161 procedures (3.7%), with no significant difference between groups (p = 0.75).

CONCLUSION

RMN-guided PV ablation provides comparable acute and long-term success rates as compared to manual navigation. Procedural complication rates are similar. The use of RMN is associated with markedly reduced fluoroscopy time, but prolonged ablation and procedure duration.

Cryoballoon catheter ablation in atrial fibrillation

Pulmonary vein isolation with catheter ablation is an effective treatment in patients with symptomatic atrial fibrillation refractory or intolerant to antiarrhythmic medications. The cryoballoon catheter was recently approved for this procedure. In this paper, the basics of cryothermal energy ablation are reviewed including its ability of creating homogenous lesion formation, minimal destruction to surrounding vasculature, preserved tissue integrity, and lower risk of thrombus formation. Also summarized here are the publications describing the clinical experience with the cryoballoon catheter ablation in both paroxysmal and persistent atrial fibrillation, its safety and efficacy, and discussions on the technical aspect of the cryoballoon ablation procedure.

Left atrial wall thickness variability measured by CT scans in patients undergoing pulmonary vein isolation

INTRODUCTION

Successful catheter ablation of atrial fibrillation (AF) requires the creation of transmural lesions in the left atrium (LA). In addition, cardiac perforation is more likely to occur in areas of thin walls. The LA wall thickness is thus relevant both for procedural efficacy and safety. This study sought to evaluate the regional LA wall thickness in patients with AF.

METHODS

The LA muscular wall thickness (excluding fat) was measured by 64 slice cardiac computed tomography (CT) in 60 patients with persistent AF prior to catheter ablation procedures. Measurements were performed in all patients at 12 distinct LA locations, including 3 at the roof (right, middle left), 3 at the floor (right, middle, left), 4 at the posterior wall (right, middle, middle-superior, left), 1 at the left lateral ridge (LLR), and 1 at the mitral isthmus.

RESULTS

There was a large range of LA wall thickness (average thickness 1.89 ± 0.48 mm, range 0.5-3.5 mm). In addition, there were significant regional differences in LA wall thickness. In particular, the LA roof was significantly thicker than the posterior wall and floor (P < 0.001), the LLR was significantly thicker than most regions (P < 0.04), and the mitral isthmus was also significantly thicker than the posterior wall (P < 0.001) and floor (P < 0.001).

CONCLUSIONS

In patients with persistent AF, there is inter- and intra-patient variability in the thickness of the LA muscular wall. In most patients, however, the roof, mitral isthmus, and the ridge between the pulmonary veins and appendage are thicker compared to the posterior wall and floor.