"Catheter ablation for atrial fibrillation has been set as second-line therapy for all patients in the treatment guidelines scheduled to be released later this year by the American College of Cardiology, the American Heart Association, and the European Society of Cardiology. By the new guidelines, patients have to fail only one drug before they become eligible for catheter ablation. This recommendation applies to all patients with atrial fibrillation, including those with concurrent heart failure, oronary artery disease, or hypertension..."
Any why not first line therapy? Well, not all folks agree on the safety and efficacy data, but there seems to be some consensus that centers with a higher volume of procedures have better outcomes.
The placement seems appropriate to me, since often patients can greatly reduce their number of episodes non-invasively with medical therapy before venturing into an ablation procedure. Also, the requirement that only ONE antiarrhythmic drug needs to be tried (especially if that drug is amiodarone, flecanide, sotalol or propafenone), permits the patient to seek non-pharmachologic therapies earlier, if desired. Note that in the substudy of the AFFIRM trial, amiodarone was the most effective antiarrhythmic medication of those listed above...