Catheter ablation of atrial fibrillation: Randomized controlled trials and registries, a look back and the view forward

Atrial fibrillation (AF) is a growing epidemic associated with a variety of adverse outcomes, including death, stroke, impaired quality of life, and increased rate of hospitalizations. Achieving a definite cure for this disease is highly desirable, as this would have outstanding social and economic implication. Catheter ablation is the only treatment demonstrated capable of eliminating AF in a substantial proportion of patients. Over the years, intense research has been directed toward the identification of the optimal ablation strategy, with the aim of increasing procedural success while minimizing complications. Multiple clinical trials have established pulmonary vein antrum isolation (PVAI) as the mainstay of treatment for paroxysmal AF patients. In these patients, the addition of superior vena cava isolation has been demonstrated to increase long-term freedom from AF recurrence compared to PVAI alone. In patients with persistent and long-standing persistent AF, a more extensive set of lesions targeting the entire left atrial posterior wall and complex fractionated electrograms (CFAE) is necessary, while those presenting for redo procedure may also benefit from ablation of other trigger sites of AF initiation, such as the left atrial appendage. With regard to safety, the most notable advances have been the introduction of open-irrigated ablation catheters and of ablation without interruption of oral anticoagulation. Both strategies have been demonstrated to reduce dramatically periprocedural thromboembolic complications, without increasing the risk of bleeding. Beyond outstanding advances in defining the optimal ablation strategies to increase the effectiveness and safety of catheter ablation, in recent years outcomes of AF treatment trials have been widely reconsidered. In addition to the prevention of AF recurrence, additional end-points have been considered important. These include reduction of hospitalization, stroke, and mortality, as well as economic factors. A correct evaluation of such end-points has required the introduction of AF ablation registries, and the design of new trials with adequate power to address such issues. This article will provide an overview of AF ablation trials that have constituted the basis for current clinical practice and will discuss the contribution of ongoing studies and registries to the future of AF ablation.