Randomised controlled trials (RCTs) that compared catheter ablation with anti-arrhythmic drug therapy in patients with atrial fibrillation were eligible for inclusion. The primary review outcome was all-cause mortality during follow-up. The secondary outcome was stroke or transient ischaemic attack.
The included trials used pulmonary vein antral ablation or circumferential pulmonary vein ablation combined with linear lesions in the left and right atria, with ablation of non-venous foci in some patients. Trials used a variety of anti-arrhythmic drugs, including a wide variety of class I and class III agents or combinations; amiodarone was used as a drug candidate in all but one trial.
In most trials patients had failed to respond to at least one anti-arrhythmic drug; in three trials patients had not previously used a membrane active anti-arrhythmic drug. Most trials were in patients with paroxysmal or persistent atrial fibrillation; one trial was in patients with chronic atrial fibrillation. The authors stated that trials were in low-risk populations with a mean age ranging from 51 to 65 years, with low rates of structural heart disease (excluding hypertension) in most trials. Included trials used different oral anti-coagulation regimens in ablation treatment groups; in most trials oral anti-coagulation was discontinued after six weeks to six months in the absence of recurrence of the arrhythmia. The duration of follow-up was one year in all except one trial, in which follow-up was nine months.
The authors did not state how many reviewers selected studies.