Identifying the soloists in the orchestra of chronic atrial fibrillation: Spectral components of subsequent atrial tachycardias in the dominant frequency of atrial fibrillation

Abstract

In contrast to paroxysmal atrial fibrillation (AF), which is uniformly confined to the pulmonary veins (PV) as the predominant structures harboring critical arrhythmogenic sources 1 Haissaguerre M. Jais P. Shah D.C. et al. Spontaneous initiation of atrial fibrillation by ectopic beats originating in the pulmonary veins. N Engl J Med. 1998; 339: 659-666 Crossref PubMed Scopus (6208) Google Scholar in the vast majority of patients, a variety of mechanisms underlie long-standing persistent (chronic) AF. Moreover, although electrical isolation of the PVs results in long-term freedom from the arrhythmia in a considerable number of patients with paroxysmal AF (as long as the PVs remain isolated over time), 2 Verma A. Kilicaslan F. Pisano E. et al. Response to atrial fibrillation to pulmonary vein antrum isolation is directly related to resumption and delay of pulmonary vein conduction. Circulation. 2005; 112: 627-635 Crossref PubMed Scopus (337) Google Scholar different standardized lesion sets, such as left atrial linear lesions in addition to PV isolation, 3 Willems S. Klemm H. Rostock T. et al. Substrate modification combined with pulmonary vein isolation improves outcome of catheter ablation in patients with persistent atrial fibrillation: a prospective randomized comparison. Eur Heart J. 2006; 27: 2871-2878 Crossref PubMed Scopus (268) Google Scholar have failed to achieve similar success rates. Thus, even though they were an attractive approach for interventional electrophysiologists, the “one size fits all” concepts did not work in the setting of chronic AF. In consideration of the individual complex mechanisms of chronic AF, new interventional concepts instead have focused on tailoring the ablation approach to patient-specific AF processes. Nademanee et al 4 Nademanee K. McKenzie J. Kosar E. et al. A new approach for catheter ablation of atrial fibrillation: mapping of the electrophysiologic substrate. J Am Coll Cardiol. 2004; 43: 2044-2053 Abstract Full Text Full Text PDF PubMed Scopus (1662) Google Scholar provided the initial key by implementing a completely new ablation strategy targeting complex fractionated atrial electrograms (CFAEs), which might represent the substrate of AF. However, the first approach that actually focused on the arrhythmia itself was introduced by Haissaguerre et al. 5 Haissaguerre M. Sanders P. Hocini M. et al. Catheter ablation of long-lasting persistent atrial fibrillation: critical structures for termination. J Cardiovascular Electrophysiol. 2005; 16: 1125-1137 Crossref PubMed Scopus (597) Google Scholar This so-called stepwise ablation approach combines the current instruments of AF ablation: PV isolation, biatrial defragmentation (including ablation of CFAEs), and linear ablation. The pioneering innovation of this concept is that the ablation procedure concentrates on the individual behavior of the arrhythmia with the intention of gradually prolonging the AF cycle length, accompanied by an organization of the fibrillatory processes, and subsequently terminating AF by ablation. To date, these individually tailored approaches usually have required a considerable amount of radiofrequency (RF) applications to reach the aimed procedure endpoints, AF termination, and further restoration of sinus rhythm (SR) by ablation. 4 Nademanee K. McKenzie J. Kosar E. et al. A new approach for catheter ablation of atrial fibrillation: mapping of the electrophysiologic substrate. J Am Coll Cardiol. 2004; 43: 2044-2053 Abstract Full Text Full Text PDF PubMed Scopus (1662) Google Scholar , 5 Haissaguerre M. Sanders P. Hocini M. et al. Catheter ablation of long-lasting persistent atrial fibrillation: critical structures for termination. J Cardiovascular Electrophysiol. 2005; 16: 1125-1137 Crossref PubMed Scopus (597) Google Scholar , 6 Haissaguerre M. Hocini M. Sanders P. et al. Catheter ablation of long-lasting persistent atrial fibrillation: clinical outcome and mechanisms of subsequent arrhythmias. J Cardiovasc Electrophysiol. 2005; 16: 1138-1147 Crossref PubMed Scopus (568) Google Scholar , 7 Rostock T. Steven D. Lutomsky B. et al. Chronic atrial fibrillation is a biatrial arrhythmia Data from catheter ablation of chronic atrial fibrillation aiming arrhythmia termination using a sequential ablation approach. Circ Arrhythmia Electrophysiol. 2008; (In press) PubMed Google Scholar Because the vast majority of patients convert to atrial tachycardia (AT) rather than directly to SR after termination of AF, and considering that a substantial number of patients have ATs as the recurrent arrhythmia during follow-up, these ablation approaches are challenged by their proarrhythmogenic potential to cause those ATs. However, the actual mechanisms behind “post-AF ATs” (proarrhythmogenic vs AF contributors) still are a matter of debate.