Reply to the Editor

Abstract

The Cox maze III procedure remains the criterion standard for treatment of standalone atrial fibrillation (AF), as well as for AF with concomitant disorders; however, it has not gained widespread acceptance because of its invasive nature.1Cox J.L. Ad N. Palazzo T. Fitzpatrick S. Suyderhoud J.P. DeGroot K.W. et al.Current status of the Maze procedure for the treatment of atrial fibrillation.Semin Thorac Cardiovasc Surg. 2000; 12: 15-19Abstract Full Text PDF Scopus (256) Google Scholar The questions arise of whether all the lesions are necessary to cure AF and whether it is necessary to expose all patients with AF to such a complex operation. Electrophysiologic studies have already identified the critical role of initiating foci, situated mainly at the orifices of the pulmonary veins.2Haïssaguerre M. Jaïs P. Shah D.C. Takahashi A. Hocini M. Quiniou G. et al.Spontaneous initiation of atrial fibrillation by ectopic beats originating in the pulmonary veins.N Engl J Med. 1998; 339: 659-666Google Scholar There is evidence suggesting that ganglionated plexuses (GPs) play an important role in the initiation and maintenance of AF.3Pappone C. Santinelli V. Manguso F. Vicedomini G. Gugliotta F. Augello G. et al.Pulmonary vein denervation enhances long-term benefit after circumferential ablation for paroxysmal atrial fibrillation.Circulation. 2004; 109: 327-334Google Scholar Adding GP ablation to pulmonary vein isolation (PVI) increases efficacy in elimination of AF.4Scherlag B.J. Nakagawa H. Jackman W.M. Yamanashi W.S. Patterson E. Po S. et al.Electrical stimulation to identify neural elements on the heart: their role in atrial fibrillation.J Interv Card Electrophysiol. 2005; 13: 37-42Google Scholar The original cut-and-sew maze procedure has been abandoned in part because of these considerations and because less invasive methods of surgical treatment for standalone AF are being developed. PVI is performed by ablation of the left atrium at the entry site of the pulmonary veins, targeted autonomic denervation, and left atrial appendage amputation, resulting in electrical isolation. The success rate with PVI alone theoretically could reach 90% for paroxysmal AF with normal atrial diameter, because most of the triggering foci are situated at the pulmonary vein ostia. In cases of persistent or long-standing AF, the role of a dilated left atrium as the substrate factor and its interplay with the trigger is important. PVI alone cannot reach the ideal success rate of 90% in cases of associated valve disease or left ventricular impairment. The ability of dry bipolar radiofrequency ablation to produce 100% permanent transmural lesions epicardially on the beating heart has been documented.5Prasad M.S. Hersh S. Diodato M.D. Schuessler R.B. Damiano Jr., R.J. Physiological consequences of bipolar radiofrequency energy on the atria and pulmonary veins: a chronic animal study.Ann Thorac Surg. 2003; 76: 836-842Google Scholar The lesions in our study were limited to PVI, and conduction block was confirmed intraoperatively. High-frequency stimulation with the unipolar multifunctional pen was performed to locate and ablate GPs in the fatty pads around the pulmonary veins; however, GPs at the left posteromedial, posterior descending, and superior atrial locations could not be reached in our study. In our series, no postoperative GP mapping was routinely performed, and the role of reinnervation thus remains uncertain. Patients in persistent or long-standing AF have associated changes in the left atrial substrate as a result of dilatation and passive mechanical stretching. This condition with atrial fibrosis can itself be arrhythmogenic, and it is therefore likely that PVI alone will be insufficient in such cases, with more extensive lesions needed to achieve a higher success rate. Our policy is to perform a thoracoscopic procedure first, even for patients with long-standing standalone AF. Only patients with refractory AF after a thoracoscopic procedure eventually undergo a maze III procedure.