Mechanisms of Atrial Fibrillation and Their Impact on Strategies for Catheter Ablation

Atrial fibrillation (AF) is the most common sustained arrhythmia, and is ubiquitous in clinical practice. The underlying mechanisms of initiation and maintenance of AF are complex and not completely understood. This knowledge, however, is fundamental for the development of treatment strategies for AF. Within the last 20 years, catheter ablation has played an increasing role as a rhythm control therapy. Based on diverse models for the initiation and maintenance of AF, various ablation strategies have been proposed. The cornerstone of AF ablation has been pulmonary vein isolation (PVI). In persistent AF, however, PVI alone is often not sufficient. This may be because of the structural remodelling of the atria leading to dilation and fibrosis amongst other factors. The optimal strategy for substrate modification, however, is still a matter of investigation. Current studies are concentrating on the ablation of fibrotic areas, especially in the left atrium, either detected by delayed enhancement magnetic resonance imaging or by identification of low-voltage areas as a surrogate marker. The second intensely evaluated strategy is the localisation and ablation of rotational activity. Many further randomised controlled trials will likely be needed to determine the optimal ablation strategy for individual patients.