Trials and Travails of Electrogram-Guided Ablation of Chronic Atrial Fibrillation

Abstract

Catheter-based ablation has revolutionized arrhythmia management by offering the most definitive treatment for virtually all types of tachyarrhythmias. The reasons behind the success of ablation are many, but chief among them is the ability of the electrophysiologist to identify underlying mechanisms and to precisely localize and eliminate the tachycardia foci or circuits. Armed with many new tools to map and ablate these arrhythmias, electrophysiologists gain experience and become more proficient in the procedure, resulting in a shortened procedure time, increased rates of success, and decreased rates of complications. As a result, catheter ablation is gradually but inexorably replacing pharmacological approach as the first-line therapy for just about all supraventricular tachyarrhythmias except atrial fibrillation (AF). Article p 2606 Unlike ablation for other types of supraventricular tachyarrhythmias, ablation of AF generally is not based on mapping of target sites for ablation; rather, it relies largely on an approach that aims to electrically isolate the pulmonary veins, especially for paroxysmal AF.1–4 The rational behind this anatomic approach is 2-fold: that the pulmonary veins are the primary sites responsible for AF initiation and perpetuation in most patients and that human AF is too complex to map and the responsible reentrant wavelets are too capricious for point-to-point mapping. However, although pulmonary vein isolation is very successful in treating paroxysmal AF, it alone is not effective in treating chronic AF. Often, supplement linear ablations are added to the pulmonary vein isolation with a significantly improved success rate.1 It has become clear that to successfully ablate chronic AF, more extensive ablations are essential, but it remains unclear why and how this combined approach works. It is possible that the multiple linear lesions (ie, a mitral isthmus line, roofline) in addition to pulmonary vein isolation effectively modify AF substrate akin to a surgical Maze procedure. However, …