Randomised controlled trials (RCTs) that compared any type of percutaneous radiofrequency catheter ablation with anti-arrhythmic drugs for the treatment of paroxysmal, persistent or long-standing persistent atrial fibrillation were eligible for inclusion. Percutaneous radiofrequency catheter ablation was described as for substrate modification or electrical isolation of pulmonary veins. Eligible trials had to follow up patients for at least six months and report any the of theoutcomes, which were recurrence of atrial tachycardia, time to recurrence of atrial tachyarrhythmia, treatment-related complications and/or adverse events. Trials were only included if they used adequate, unclear or inadequate allocation concealment and scored at least 3 out of 5 points on the Jadad quality scale.
Most of the included trials used segmental ostial ablation of the pulmonary vein as the main ablation technique; some trials used circumferential pulmonary vein ablation. In all but one trial, the protocol included adjunctive ablation lines in the right and left atria and/or ablation of complex fractionated electrograms in the left atrium. In most trials, concomitant anti-arrhythmic drugs were given for four and 12 weeks after the ablation treatment. Where specified, anti-arrhythmic drugs included amiodarone, flecainide and sotalol.
All but one trial considered a blanking period from 1.5 to three months after ablation when reporting arrhythmias. Most trials monitored heart rhythm using daily brief event monitoring; other trials used periodic Holter monitoring, weekly brief event monitoring or patient-assessed pulse monitoring.
Approximately two-thirds of patients had symptomatic paroxysmal atrial fibrillation; the other third had persistent or long-standing persistent atrial fibrillation. Most patients had an absence of structural heart disease or heart disease with normal left ventricular function. Most trials were of patients with atrial fibrillation who had failed to respond to at least one or two anti-arrhythmic drugs or were intolerant of anti-arrhythmic drugs. The mean age of patients ranged from 49 to 65 years across treatment groups. Most patients were male.
One reviewer identified eligible studies from titles and abstracts. Decisions on studies to completely review were made by consensus. Two reviewers then selected studies for inclusion. Disagreements were resolved by discussion with a third reviewer.