Reply: The best patient for the operation, or the best operation for the patient?

Dr Damiano is a speaker and receives research funding from Atricure, Inc; is a speaker, consultant, and received research funding from Medtronic; and is a speaker, consultant, and receives research funding from Edwards Lifesciences. The other author reported no conflicts of interest.The Journal policy requires editors and reviewers to disclose conflicts of interest and to decline handling or reviewing manuscripts for which they may have a conflict of interest. The editors and reviewers of this article have no conflicts of interest. Dr Damiano is a speaker and receives research funding from Atricure, Inc; is a speaker, consultant, and received research funding from Medtronic; and is a speaker, consultant, and receives research funding from Edwards Lifesciences. The other author reported no conflicts of interest. The Journal policy requires editors and reviewers to disclose conflicts of interest and to decline handling or reviewing manuscripts for which they may have a conflict of interest. The editors and reviewers of this article have no conflicts of interest. We thank Garcia-Villarreal for his recent letter,1García-Villarreal O.A. The importance of the critical mass concept in the Cox-maze procedure.J Thorac Cardiovasc Surg. 2023;XXX:XXX; https://doi.org/10.1016/j.jtcvs.2022.12.007Abstract Full Text Full Text PDF Scopus (1) Google Scholar written in response to our study on the efficacy of the Cox-maze IV (CMP-IV) procedure in patients with giant left atria (GLA).2McGilvray M.M.O. Bakir N.H. Yates T.A.E. Kelly M.O. Sinn L.A. Zemlin C.W. et al.Surgical ablation for atrial fibrillation is efficacious in patients with giant left atria.J Thorac Cardiovasc Surg. November 25, 2022 [Epub ahead of print]; https://doi.org/10.1016/j.jtcvs.2022.10.058Abstract Full Text Full Text PDF Scopus (1) Google Scholar We are grateful for the opportunity to clarify and further emphasize our major points. Our goal was to inform surgical decision making, specifically addressing the issue as to whether large left atrium (LA) size should be a contraindication to the CMP-IV in patients with atrial fibrillation (AF). In our retrospective single-center experience, we found that patients with GLA who underwent a CMP-IV procedure with full posterior LA box isolation had good rhythm outcomes, statistically equivalent to those for patients without GLA. Specifically, we found that upon competing risks analysis, estimated time to first atrial tachyarrhythmia (ATA) recurrence or death was statistically indistinguishable between groups (Gray test P = .442). We employed the definition of GLA as LA diameter >6.5 cm,3Apostolakis E. Shuhaiber J.H. The surgical management of giant left atrium.Eur J Cardio Thorac Surg. 2008; 33: 182-190Crossref PubMed Scopus (72) Google Scholar whereas Garcia-Villarreal1García-Villarreal O.A. The importance of the critical mass concept in the Cox-maze procedure.J Thorac Cardiovasc Surg. 2023;XXX:XXX; https://doi.org/10.1016/j.jtcvs.2022.12.007Abstract Full Text Full Text PDF Scopus (1) Google Scholar cited a different definition of GLA, with a diameter threshold of 8 cm. The popularity of particular definitions in various practice locations is likely reflective of the prevalence of large LA diameters within a specific patient population. As we describe in our article, in our practice it is rare to have a patient with LA diameter >8 cm.2McGilvray M.M.O. Bakir N.H. Yates T.A.E. Kelly M.O. Sinn L.A. Zemlin C.W. et al.Surgical ablation for atrial fibrillation is efficacious in patients with giant left atria.J Thorac Cardiovasc Surg. November 25, 2022 [Epub ahead of print]; https://doi.org/10.1016/j.jtcvs.2022.10.058Abstract Full Text Full Text PDF Scopus (1) Google Scholar We used the definition most relevant for our patients. Garcia-Villarreal also noted that when viewed as a continuous variable, LA diameter has been associated with increased risk of ATA recurrence after surgical ablation.1García-Villarreal O.A. The importance of the critical mass concept in the Cox-maze procedure.J Thorac Cardiovasc Surg. 2023;XXX:XXX; https://doi.org/10.1016/j.jtcvs.2022.12.007Abstract Full Text Full Text PDF Scopus (1) Google Scholar As noted in our study, we also saw this trend: Upon binary logistic regression, for every 1-cm increase in LA diameter, the estimated odds of ATA recurrence within 5 years of operation increased by 37%.2McGilvray M.M.O. Bakir N.H. Yates T.A.E. Kelly M.O. Sinn L.A. Zemlin C.W. et al.Surgical ablation for atrial fibrillation is efficacious in patients with giant left atria.J Thorac Cardiovasc Surg. November 25, 2022 [Epub ahead of print]; https://doi.org/10.1016/j.jtcvs.2022.10.058Abstract Full Text Full Text PDF Scopus (1) Google Scholar Indeed, the critical-mass hypothesis—in which there is a theoretical critical-mass of tissue needed to sustain AF—has undergone in-depth investigation in several published studies, including the study Garcia-Villarreal cited from our laboratory, which was the first to define the critical-mass needed to sustain AF as a function of increasing atrial area and decreasing effective refractory period via a robust experimental model. The CMP-IV procedure's success in part comes from its ability to decrease the electrically active mass of the LA by electrically isolating the entire posterior LA, without the need to mechanically resect tissue. As the LA increases in size, so too does the area that is electrically isolated by the CMP-IV procedure posterior LA box lesion. We believe the development of the AF substrate represents an interaction between varied pathophysiological mechanisms, including not only LA volume but also fibrosis and electrical remodeling. The latter 2 changes may occur independent of an increase in LA volume—indeed, the majority of our AF patients do not have GLA. We are not aware of any published data supporting that fibrosis causes increased conduction velocity or decreased effective refractory period as suggested by Garcia-Villarreal's letter.1García-Villarreal O.A. The importance of the critical mass concept in the Cox-maze procedure.J Thorac Cardiovasc Surg. 2023;XXX:XXX; https://doi.org/10.1016/j.jtcvs.2022.12.007Abstract Full Text Full Text PDF Scopus (1) Google Scholar Indeed, fibrosis has been associated with slowed conduction and increased conduction inhomogeneity,4Burstein B. Comtois P. Michael G. Nishida K. Villeneuve L. Yeh Y.-H. et al.Changes in connexin expression and the atrial fibrillation substrate in congestive heart failure.Circ Res. 2009; 105: 1213-1222Crossref PubMed Scopus (160) Google Scholar both of which could in turn decrease the critical-mass needed to sustain AF, without a corresponding increase in atrium size. As such, it is unlikely that a simple metric such as LA diameter will ever be an adequate descriptor of this disease. Our goal in the present study2McGilvray M.M.O. Bakir N.H. Yates T.A.E. Kelly M.O. Sinn L.A. Zemlin C.W. et al.Surgical ablation for atrial fibrillation is efficacious in patients with giant left atria.J Thorac Cardiovasc Surg. November 25, 2022 [Epub ahead of print]; https://doi.org/10.1016/j.jtcvs.2022.10.058Abstract Full Text Full Text PDF Scopus (1) Google Scholar was to answer a pressing, practical issue for today's arrhythmia surgeons. Should we offer a maze procedure to patients with large LAs, even though available data suggest that these patients have a higher risk of ATA recurrence? Based on our study results, our answer to that question is an emphatic yes. That is, LA size alone should not preclude a patient from receiving the most efficacious available treatment for AF, therefore denying him or her the survival and quality of life benefits of the CMP-IV.5Musharbash F.N. Schill M.R. Sinn L.A. Schuessler R.B. Maniar H.S. Moon M.R. et al.Performance of the Cox-maze IV procedure is associated with improved long-term survival in patients with atrial fibrillation undergoing cardiac surgery.J Thorac Cardiovasc Surg. 2018; 155: 159-170Abstract Full Text Full Text PDF PubMed Scopus (59) Google Scholar Ultimately, the issue is one of perspective—the best patient for the operation, or the best operation for the patient. For the prospective patient with AF and a large LA, there are 3 options: no ablation, which leaves the majority of patients in AF and impairs late survival6Andrade J.G. Wells G.A. Deyell M.W. Bennett M. Essebag V. Champagne J. et al.Cryoablation or drug therapy for initial treatment of atrial fibrillation.N Engl J Med. 2021; 384: 305-315Crossref PubMed Scopus (267) Google Scholar; catheter-based ablation, which has high failure rates, especially in patients with GLA6Andrade J.G. Wells G.A. Deyell M.W. Bennett M. Essebag V. Champagne J. et al.Cryoablation or drug therapy for initial treatment of atrial fibrillation.N Engl J Med. 2021; 384: 305-315Crossref PubMed Scopus (267) Google Scholar,7den Uijl D.W. Delgado V. Bertini M. Tops L.F. Trines S.A. van de Veire N.R. et al.Impact of left atrial fibrosis and left atrial size on the outcome of catheter ablation for atrial fibrillation.Heart. 2011; 97: 1847-1851Crossref PubMed Scopus (101) Google Scholar; or a CMP-IV procedure, with an 81% rate of recurrence-free survival at 1 year, as seen in our GLA cohort. Given these options, if the patient is a reasonable operative candidate, we believe that the decision is clear—the best treatment for these patients is a CMP-IV procedure. The importance of the critical mass concept in the Cox–maze procedureThe Journal of Thoracic and Cardiovascular SurgeryPreviewI have read with interest the article by McGilvray and colleagues1 in which they have reported the results after Cox–maze procedure (CMP), with special focus on 72 patients having a giant left atrium (GLA) at 5-year follow-up. They found no important difference in terms of freedom from atrial fibrillation (AF), regardless of whether the left atrial (LA) size was >6.5 cm or <6.5 cm (82% vs 84%), respectively. This finding deserves special attention in terms of the feasibility of CMP. Full-Text PDF