Ablation of Focal Impulses and Rotational Sources: What Can Be Learned from Differing Procedural Outcomes?

Introduction: There is considerable interest in identifying potential drivers for human atrial fibrillation (AF), in order to improve therapy. Ablation via pulmonary vein isolation (PVI) is broadly used, yet is insufficient in many patients yet its outcomes are unimproved by adding extensive ablation of lines or complex electrogram sites, particularly in patients with persistent AF. Novelty: Rotational and focal sources for AF represent novel mechanistic and therapeutic targets, often remote from the PVs and proven to drive AF in many studies. This chapter discusses this issue. Aspects of Clinical Relevance: AF sources can now routinely be identified clinically by many methods, yet discrepant results have been reported. AF drivers identified by Focal Impulse and Rotor Mapping (FIRM), the most widely applied method, are also seen in simultaneous optical maps of human atria and have now been detected by other mapping methods applied to the exact same signals. In proof-of-concept studies, ablation of drivers can terminate persistent AF and, in over a thousand patients reported thus far, yield favorable long-term outcomes versus PVI alone. Nevertheless, some centers show disappointing results. This review focuses on discrepant results, which may reflect challenging patients, operator unfamiliarity with basket catheter use, or the technical ablation of drivers, amongst other factors. We discuss challenges, potential solutions, and future directions for map-guided AF driver ablation including basket-data collection, interpreting AF maps, ablation guidance, and extent. Conclusions: Mapping and ablation of AF drivers is a rapidly growing field which, with continued scientific discovery and procedural advances, offers a strong mechanistic foundation to improve patient-tailored ablation for complex arrhythmias. © 2017, Springer Science+Business Media, LLC.