Deconstructing complex fractionated atrial electrograms: Just how complex and fractionated are they?

Few topics in clinical electrophysiology evoke as much controversy as that of complex fractionated atrial electrograms (CFAEs). The original description by Nademanee et al 1 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 Google Scholar offered electrophysiologists a tool by which to map and ablate the atrial “substrate” in patients with atrial fibrillation (AF). Subsequent studies have reached disparate conclusions, with some suggesting that ablation of CFAEs has a role in patients with persistent AF 2 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 Google Scholar , 3 Elayi C.S. Verma A. Di Biase L. et al. Ablation for longstanding permanent atrial fibrillation: results from a randomized study comparing three different strategies. Heart Rhythm. 2008; 5: 1658-1664 Google Scholar and others not. 4 Oral H. Chugh A. Yoshida K. et al. A randomized assessment of the incremental role of ablation of complex fractionated atrial electrograms after antral pulmonary vein isolation for long-lasting persistent atrial fibrillation. J Am Coll Cardiol. 2009; 53: 782-789 Google Scholar Apart from the lack of consensus in the literature, there is no universal definition of what constitutes a CFAE. Furthermore, a CFAE may be generated by a variety of mechanisms, all of which may not be critical to the fibrillatory process. These complex electrograms may be found at areas of slow conduction, 5 Konings K.T. Smeets J.L. Penn O.C. Wellens H.J. Allessie M.A. Configuration of unipolar atrial electrograms during electrically induced atrial fibrillation in humans. Circulation. 1997; 95: 1231-1241 Google Scholar pivot point of turning wavelets, wave collision, fibrillatory conduction, 6 Vaquero M. Calvo D. Jalife J. Cardiac fibrillation: from ion channels to rotors in the human heart. Heart Rhythm. 2008; 5: 872-879 Google Scholar rotor meandering, 7 Zlochiver S. Yamazaki M. Kalifa J. Berenfeld O. Rotor meandering contributes to irregularity in electrograms during atrial fibrillation. Heart Rhythm. 2008; 5: 846-854 Google Scholar or autonomic activation. 8 Lu Z. Scherlag B.J. Lin J. et al. Autonomic mechanism for complex fractionated atrial electrograms: evidence by fast fourier transform analysis. J Cardiovasc Electrophysiol. 2008; 19: 835-842 Google Scholar Currently it is not possible to predict prior to ablation whether a given CFAE is being generated by a driver source versus a bystander site. This is an important point because excessive ablation not only is time consuming but also may be associated with acute and long-term complications such as atrial scarring 9 Chan C.P. Wong W.S. Pumprueg S. et al. Inadvertent electrical isolation of the left atrial appendage during catheter ablation of persistent atrial fibrillation. Heart Rhythm. 2010; 7: 173-180 Google Scholar and impairment of atrial mechanical function. To add to this conundrum, a recent study questioned the validity of sequential mapping of CFAEs on the basis of their temporal variability. 10 Habel N. Znojkiewicz P. Thompson N. et al. The temporal variability of dominant frequency and complex fractionated atrial electrograms constrains the validity of sequential mapping in human atrial fibrillation. Heart Rhythm. 2010; 7: 586-593 Google Scholar Classifying fractionated electrograms in human atrial fibrillation using monophasic action potentials and activation mapping: Evidence for localized drivers, rate acceleration, and nonlocal signal etiologiesHeart RhythmVol. 8Issue 2PreviewComplex fractionated electrograms (CFAEs) detected during substrate mapping for atrial fibrillation (AF) reflect etiologies that are difficult to separate. Without knowledge of local refractoriness and activation sequence, CFAEs may represent rapid localized activity, disorganized wave collisions, or far-field electrograms. Full-Text PDF