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Do Not Forget the Mechanisms and Ablation Techniques of
Atrial Fibrillation Beyond the Pulmonary Veins
MING-HSIUNG HSIEH, M.D.
∗,
† and SHIH-ANN CHEN, M.D.‡
From the∗Division of Cardiovascular Medicine, Department of Medicine, Taipei Medical University, School of Medicine, and Taipei Wan-Fang Hospital;†Division of Cardiology, Department of Medicine, Cardiovascular Research Institute, National Yang-Ming University
School of Medicine, and Taipei Veterans General Hospital; and‡Institute of Clinical Medicine, National Yang-Ming University School of Medicine, Taipei, Taiwan
Editorial Comment
Ever since the pulmonary veins (PVs) were identified as the major trigger of atrial fibrillation (AF), catheter ablation of the PVs has become the mainstream nonpharmacologic therapy for the treatment of AF.1,2Currently, the techniques used for ablation of AF include one or a combination of the following techniques: isolation of the PVs (segmental or cir-cumferential approach) with or without demonstration of PV-left atrial conduction block, PV-left atrial linear ablation (mitral isthmus, roof, and posterior wall), ablation of the complex fractionated electrograms, and ablation of the autonomic gan-glions.3-6In this decade of AF ablation, we have really been
performing AF ablation with the “learning while burning” strategy. In this issue of the Journal of Cardiovascular
Elec-trophysiology, Pak et al. used the noncontact balloon mapping
technique to identify AF triggers and to demonstrate the atrial activation characteristics following the triggers.7They found that the persistent AF patients had a higher incidence of non-PV triggers compared with the paroxysmal AF patients, and the preferential conduction following the trigger activation was mostly located along the roof area. These novel results improve our current knowledge of AF mechanisms and pro-vide further insight into the ablation techniques for AF.
AF Beyond the PVs
The non-PV triggers are important for the initiation of AF, and non-PV substrates are important for the initiation and maintenance of AF.8-12 The reason why we continue to
perform provocation testing to find the AF triggers before and after PV isolation is to search for possible non-PV foci.8-11
The non-PV foci may contribute to 10–20% of the triggers in patients with paroxysmal AF and there may be an even higher incidence in persistent AF.7-12 To improve the
clini-cal outcome of AF ablation, detailed mapping and ablation of non-PV foci are necessary. Both the right and left atria, including the LA appendage, LA posterior wall, ligament of Marshall, superior vena cava, crista terminalis, coronary si-nus, interatrial septum, etc., are possible trigger sites.8-10It is
important to recognize that in a small proportion of patients, AF can be cured after only ablation of the non-PV triggers, and the right atrial triggers are important for very late (more
J Cardiovasc Electrophysiol, Vol. 17, pp. 825-826, August 2006.
Address for correspondence: Shih-Ann Chen, M.D., Division of Cardiology, Taipei Veterans General Hospital, 201 Sec. 2, Shih-Pai Road, Taipei, Taiwan, R.O.C. Fax: 886-2-2873-5656; E-mail: epsachen@ms41.hinet.net doi: 10.1111/j.1540-8167.2006.00529.x
than 1 year after the first ablation procedure) recurrence of AF.11,13
Kumagai et al. performed one elegant study with a basket catheter inside the PV and around the PV-left atrial junction, and demonstrated that the AF drivers were around the PV-left atrial junction.14 Recently, the Taipei and Bordeaux groups
have reported novel findings of AF drivers located away from the PV-left atrial junction, and AF can be cured after ablation of those non-PV drivers.11,12Lin et al. used the noncontact balloon mapping technique to identify single or double loop reentry with fibrillatory conduction in the right atrium, and ablation of the critical substrate for the maintenance of the AF could cure 85% of paroxysmal AF that was initiated by a driver (not initiated by an ectopic trigger).11Recently, Haissa-guerre et al. also identified a trigger and driver of AF outside the PVs after isolation of the four PVs and linear ablation of the mitral isthmus and roof in patients with chronic AF.12
They also used a flower catheter for extensive mapping, and proposed this type of AF was caused by a reentry mechanism. The findings from Pak et al. further confirmed the impor-tant role of non-PV triggers in the initiation of persistent AF, and the atrial substrate located in the left atrial roof is im-portant for the maintenance of AF.7Therefore, identification of atrial arrhythmogenesis beyond the PVs is important for understanding the mechanisms and ablation techniques for the treatment of AF.
Mechanisms Versus Ablation Techniques for Curing AF—Which Is Important?
AF has a quite variable clinical presentation, from lone AF to severe organic heart disease, and from no symptoms to frequent symptomatic attacks. AF is also the most common sustained arrhythmia, and might also be the most complex arrhythmia. We should consider several important issues be-fore we choose the optimal ablation technique. First, have the mechanisms of AF in the animal model been proven in human AF? Second, are the AF mechanisms between parox-ysmal and persistent AF similar? Are they similar between young and older patients? Are they similar between idio-pathic AF and patients with structural heart disease? Third, does every AF patient have only one AF mechanism or sev-eral AF mechanisms? Fourth, does every AF patient need only one ablation technique or a combination of several ablation techniques to cure the AF? It is clear that further investiga-tion into these issues is necessary before we can obtain the right answers. Although some ablation techniques have been established after carrying out several clinical trials in large volume centers, the presentation of a high success rate of AF ablation in the future should not be the golden rule for the
826 Journal of Cardiovascular Electrophysiology Vol. 17, No. 8, August 2006
electrophysiologists worldwide who are devoted to curing AF. How to identify the clinical mechanisms of AF, and how to tailor the ablation techniques for both paroxysmal and per-sistent AF are the most important challenges we face.
References
1. Haissaguerre M, Jais P, Shah DC, Takahashi A, Hocini M, Quiniou G, Garrigue S, Le Mouroux A, Le Metayer P, Clementy J: Spontaneous ini-tiation of atrial fibrillation by ectopic beats originating in the pulmonary veins. N Engl J Med 1998;339:659-666.
2. Chen SA, Hsieh MH, Tai CT, Tsai CF, Prakash VS, Yu WC, Hsu TL, Ding YA, Chang MS: Initiation of atrial fibrillation by ectopic beats originating from the pulmonary veins: Electrophysiological characteris-tics, pharmacological responses, and effects of radiofrequency ablation. Circulation 1999;100:1879-1886.
3. Pappone C, Rosanio S, Oreto G, Tocchi M, Gugliotta F, Vicedomini G, Salvati A, Dicandia C, Mazzone P, Santinelli V, Gulletta S, Chier-chia S: Circumferential radiofrequency ablation of pulmonary vein os-tia: A new anatomic approach for curing atrial fibrillation. Circulation 2000;102:2619-2628.
4. 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.
5. Haissaguerre M, Hocini M, Sanders P, Sacher F, Rotter M, Takahashi Y, Rostock T, Hsu LF, Bordachar P, Reuter S, Roudaut R, Clementy J, Jais P: Catheter ablation of long-lasting persistent atrial fibrillation: Clini-cal outcome and mechanisms of subsequent arrhythmias. J Cardiovasc Electrophysiol 2005;16:1138-1147.
6. Scherlag BJ, Nakagawa H, Jackman WM, Yamanashi WS, Patterson E, Po S, Lazzara R: Electrical stimulation to identify neural elements on
the heart: Their role in atrial fibrillation. J Interv Card Electrophysiol 2005;13 (Suppl 1):37-42.
7. Pak HN, Hwang C, Lim HE, Kim JW, Lee SH, Kim YH: Elec-troanatomic characteristics of atrial premature beats triggering atrial fibrillation in patients with persistent versus paroxysmal atrial fibrilla-tion. J Cardiovasc Electrophysiol 2006;17:818-824.
8. Lin WS, Tai CT, Hsieh MH, Tsai CF, Lin YK, Tsao HM, Huang JL, Yu WC, Yang SP, Ding YA, Chang MS, Chen SA: Catheter ablation of paroxysmal atrial fibrillation initiated by non-pulmonary vein ectopy. Circulation 2003;107:3176-3183.
9. Shah D, Haissaguerre M, Jais P, Hocini M: Nonpulmonary vein foci: Do they exist? Pacing Clin Electrophysiol 2003;26:1631-1635. 10. Saksena S, Skadsberg ND, Rao HB, Filipecki A: Biatrial and
three-dimensional mapping of spontaneous atrial arrhythmias in patients with refractory atrial fibrillation. J Cardiovasc Electrophysiol 2005;16:494-504.
11. Lin YJ, Tai CT, Kao T, Tsao HW, Huang JL, Higa S, Yuniadi Y, Huang BH, Liu TY, Lee PC, Hsieh MH, Chen SA: Electrophysiological char-acteristics and catheter ablation in patients with paroxysmal right atrial fibrillation. Circulation 2005;112:1692-1700.
12. Haissaguerre M, Hocini M, Sanders P, Takahashi Y, Rotter M, Sacher F, Rostock T, Hsu LF, Jonsson A, O’Neill MD, Bordachar P, Reuter S, Roudaut R, Clementy J, Jais P: Localized sources maintaining atrial fibrillation organized by prior ablation. Circulation 2006;113:616-625. 13. Hsieh MH, Tai CT, Lee SH, Lin YK, Tsao HM, Chang SL, Lin YJ, Wongchaoen W, Lee KT, Chen SA: The different mechanisms between late and very late recurrences of atrial fibrillation in patients undergoing a repeated catheter ablation. J Cardiovasc Electrophysiol 2006;17:231-235.
14. Kumagai K, Ogawa M, Noguchi H, Yasuda T, Nakashima H, Saku K: Electrophysiologic properties of pulmonary veins assessed using a multielectrode basket catheter. J Am Coll Cardiol 2004;43:2281-2289.
