Complex fractionated atrial electrograms (CFAE)

Complex fractionated atrial electrograms (CFAE)

Complex fractionated atrial electrograms (CFAE) were offered as a tool for substrate mapping and ablation in atrial fibrillation by Nademanee K et al in 2004 [1]. But there is a lack of consensus on the definition of CFAE as well as the definite role in ablation of atrial fibrillation. Complex fractionated atrial electrograms may be found at areas of slow conduction, pivot point of turning wavelets, wave collision, fibrillatory conduction, rotor meandering as well as due to autonomic activation. But all CFAEs may not be the driver source for atrial fibrillation. This has an important implication in that searching for and ablating all CFAE locations may be time consuming and produce unnecessary atrial scarring or even atrial mechanical dysfunction. More over temporal variability of CFAE locations have also been described, questioning the utility of CFAE mapping.

Narayan SM et al [2] have classified complex fractionated atrial electrograms into four types using monophasic action potentials:

1. Type I – CFAE with rapid regular and pansystolic activation
2. Type II – Acceleration-dependent CFAE (both contributing eight percent each)
3. Type III – CFAE due to nonlocal (far-field) electrogram detection, which appears to be the commonest variety (67%)
4. Type IV – CFAE without discrete monophasic action potentials (MAP) and “disorganized atrial fibrillation” which constituted seventeen percent. It may be noted that CFAE due to far-field signals may not be ideal ablation sites.

The Substrate and Trigger Ablation for Reduction of Atrial Fibrillation – Part II (STAR AF II) trial evaluated three strategies for ablation of persistent atrial fibrillation [3]. The strategies were pulmonary vein isolation, pulmonary vein isolation plus CFAE ablation and pulmonary vein isolation plus linear lesions. The study randomized 589 patients with persistent atrial fibrillation. Procedure time was significantly shorter for pulmonary vein isolation alone, as expected (P<0.001). After 18 months, the percentage of patients free of recurrent atrial fibrillation in the three groups were 59%, 49% and 46% respectively. But the difference was not statistically significant  (P=0.15).

Another smaller study randomized 92 patients with persistent atrial fibrillation (AF) to pulmonary vein isolation plus ablation of CFAE or pulmonary vein isolation plus additional linear ablation across the left atrial roof and mitral valve isthmus [4]. Follow up was longer, for a period was 5 years. At 12 month follow up, AF recurrence rates were 21% and 23% respectively. At a mean follow up of 59±36 months the figures were 44.6% and 48.3% respectively, which was not a statistically significant difference. Authors concluded that among patients with persistent atrial fibrillation, there was no difference in maintenance of sinus rhythm between CFAE ablation or linear ablation performed in addition to pulmonary vein isolation, either in short term or long term follow up.

References

1. Nademanee K, McKenzie J, Kosar E, Schwab M, Sunsaneewitayakul B, Vasavakul T, Khunnawat C, Ngarmukos T. A new approach for catheter ablation of atrial fibrillation: mapping of the electrophysiologic substrate. J Am Coll Cardiol. 2004; 43: 2044–2053.
2. Narayan SM, Wright M, Derval N, Jadidi A, Forclaz A, Nault I, Miyazaki S, Sacher F, Bordachar P, Clémenty J, Jaïs P, Haïssaguerre M, Hocini M. Classifying fractionated electrograms in human atrial fibrillation using monophasic action potentials and activation mapping: Evidence for localized drivers, rate acceleration, and nonlocal signal etiologies. Heart Rhythm. 2011;8:244-253.
3. Verma A, Jiang CY, Betts TR, Chen J, Deisenhofer I, Mantovan R, Macle L, Morillo CA, Haverkamp W, Weerasooriya R, Albenque JP, Nardi S, Menardi E, Novak P, Sanders P; STAR AF II Investigators. Approaches to catheter ablation for persistent atrial fibrillation. N Engl J Med. 2015 May 7;372(19):1812-22.
4. Deshmukh A, Zhong L, Slusser J, Xiao P, Zhang P, Hodge D, Hocini M, McLeod C, Bradley D, Munger T, Packer D, Cha YM. Anatomy Versus Physiology-Guided Ablation for Persistent Atrial Fibrillation. J Atr Fibrillation. 2020 Apr 30;12(6):2280.