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A systematic review of randomized trials comparing radiofrequency ablation with antiarrhythmic medications in patients with atrial fibrillation

GM Nair, PB Nery, S Diwakaramenon, JS Healey, SJ Connolly, and CA Morillo.

Review published: 2009.

CRD summary

This generally well-conducted review concluded that radiofrequency ablation reduced the risk of atrial fibrillation recurrence at one year by 65 per cent in patients with paroxysmal and persistent atrial fibrillation and structurally normal hearts, compared with antiarrhythmic medications. Further large trials were needed for confirmation of efficacy and safety. The cautious conclusions are likely to be reliable.

Authors' objectives

To compare radiofrequency ablation with antiarrhythmic medications in the treatment of patients with atrial fibrillation.

Searching

EMBASE, MEDLINE, Cochrane Central Register of Controlled Trials, DARE, Cochrane Database of Systematic Reviews, International Pharmaceutical Abstracts and Web of Science databases were searched without restriction of language or publication status up to February 2008. Also searched were seven trial registries, the FDA and abstracts of several relevant conferences for the previous five years. References of included studies were checked.

Study selection

Randomised controlled trials (RCTs) that compared radiofrequency ablation with antiarrhythmic medications in the treatment of patients with atrial fibrillation were eligible for inclusion. The primary outcome was recurrence of atrial fibrillation.

All except one included study enrolled patients who had failed with or were intolerant to at least one or two antiarrhythmic medications. The studies enrolled patients with paroxysmal or persistent atrial fibrillation. Approximately two-thirds of all patients had structural heart disease. Patients in all studies were given systemic anticoagulation therapy from at least four weeks prior to surgery and for at least three months afterwards. Most were treated with amiodarone for two to three months post-operatively. All except one study used a hybrid approach to radiofrequency ablation, which included pulmonary vein isolation along with linear ablation and ablation of complex fractionated electrograms in the left and right atria. The remaining study performed only pulmonary vein isolation. Most studies were performed in high-volume centres. Full details of catheter types, power settings and surgical procedures were reported. Electrophysiological endpoints were used to determine successful ablation. Ambulatory electrocardiogram monitors or transtelephonic monitors were used to detect atrial fibrillation. Secondary outcomes of quality of life, hospitalisation rates and procedure-related complications were also reported.

Two reviewers independently assessed the studies for inclusion in the review.

Assessment of study quality

The studies were assessed for validity using a tool adapted from a published instrument that assessed the following criteria: randomisation; clarity of research question and inclusion criteria; multicentre trial; allocation concealment; blinding of patients, caregivers and outcome assessors; use of intention-to-treat analysis; appropriate statistical analysis; follow-up; and treatment of patients lost to follow-up. Studies were given a score out of a maximum of 13 points: those scoring 5 or less were classed as poor quality; those scoring between 6 and 9 points were intermediate quality; and those scoring 10 or more points were classed as high quality. It appeared that two reviewers independently performed the validity assessment.

Data extraction

Two reviewers independently performed the data extraction. Disagreements were resolved through consensus or adjudication by a third reviewer.

Methods of synthesis

Intention-to-treat data was pooled in a random-effects meta-analysis to calculate a pooled risk ratio (RR) with 95% confidence intervals (CI) for the recurrence of atrial fibrillation after one year of treatment. Statistical heterogeneity was assessed using the Χ2 and I2 tests, with I2 greater than 60% considered to denote significant heterogeneity. A sensitivity analysis excluding a trial published as an abstract was carried out. Further sensitivity analyses based on trial characteristics and quality were performed.

Results of the review

Six RCTs (n=693) were included in the review. Four RCTs had moderate-to-high quality, with summary scores of 9 or 10 points. Two studies scored fewer than 5 points and were considered poor quality. Three trials reported significant crossover from the control to the intervention arm.

There was a statistically significantly lower recurrence of atrial fibrillation at one year in the radiofrequency groups (risk ratio was 0.33, 95% CI: 0.21 to 0.51, p<0.001; six RCTs, n=693). The absolute risks of recurrence were 24 per cent in the radiofrequency ablation groups compared with 73 per cent in the control groups. There was statistically significant heterogeneity in the analysis (Χ2 p<0.001, I2=75.9%). Exclusion of the trial reported only as an abstract did not significantly alter the results of the analysis (risk ratio was 0.35, 95% CI: 0.21 to 0.57, p<0.001; five trials), which also showed significant heterogeneity. Further sensitivity analyses failed to explain the heterogeneity.

Authors' conclusions

In selected patients with atrial fibrillation, radiofrequency ablation reduced the risk of atrial fibrillation recurrence at one year by 65 per cent in patients with paroxysmal and persistent atrial fibrillation and structurally normal hearts, compared with antiarrhythmic medications. Large well-designed multicentre trials were needed to confirm the efficacy and safety of radiofrequency ablation.

CRD commentary

The review question and inclusion criteria were clear and specific. The authors searched several databases and other sources without restrictions on language or publication status, reducing the chances that relevant studies were omitted and that bias was introduced. Procedures to minimise reviewer bias and error were reported for all stages of the review process. The validity assessment used appropriate criteria and was used to inform the synthesis. The use of meta-analysis appeared appropriate based on the clinical and methodological characteristics of the trials. Reasonable steps were taken to assess and explore statistical heterogeneity. The authors' conclusions accurately reflected the results of the review and showed appropriate caution in the light of differences between the included studies and the quality of these studies. These conclusions are, therefore, likely to be reliable.

Implications of the review for practice and research

Practice: The authors did not state any implications for practice.

Research: The authors stated that there was a need for large well-designed multicentre trials to confirm the efficacy and safety of radiofrequency ablation for atrial fibrillation. They also highlighted the need for research into radiofrequency ablation as a first-line therapy for atrial fibrillation.

Funding

Biosense-Webster, St Jude Medical Canada, J&J, Medtronic Canada.

Bibliographic details

Nair G M, Nery P B, Diwakaramenon S, Healey J S, Connolly S J, Morillo C A. A systematic review of randomized trials comparing radiofrequency ablation with antiarrhythmic medications in patients with atrial fibrillation. Journal of Cardiovascular Electrophysiology 2009; 20(2): 138-144. [PubMed: 18775040]

Indexing Status

Subject indexing assigned by NLM

MeSH

Anti-Arrhythmia Agents /adverse effects /therapeutic use; Atrial Fibrillation /drug therapy /surgery; Catheter Ablation /adverse effects; Electrocardiography; Humans; Publication Bias; Randomized Controlled Trials as Topic /standards; Treatment Outcome

AccessionNumber

12009103142

Database entry date

05/08/2009

Record Status

This is a critical abstract of a systematic review that meets the criteria for inclusion on DARE. Each critical abstract contains a brief summary of the review methods, results and conclusions followed by a detailed critical assessment on the reliability of the review and the conclusions drawn.

CRD has determined that this article meets the DARE scientific quality criteria for a systematic review.

Copyright © 2014 University of York.

PMID: 18775040

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