The Impact of Left Atrial Reduction during Surgical Ablation of Atrial Fibrillation

Take Home Message

  • The removal of the left atrial appendage is an essential part of the Cox-maze procedure. As such, it is directly related to the low stroke rate after operation. This fact must be always considered when analyzing the final benefits of the Cox-maze procedure. 
  • La eliminación o resección de la orejuela izquierda es parte esencial del procedimiento de Cox-maze. Como tal, está directamente relacionada con la baja incidencia de accidente cerebrovascular después del procedimiento. Este hecho debe tenerse siempre en cuenta al analizar los beneficios finales del procedimiento Cox-maze.
  • A remoção ou ressecção do apêndice esquerdo é uma parte essencial do procedimento do Cox-maze. Como tal, está diretamente relacionado à baixa incidência de AVC após o procedimento. Esse fato deve sempre ser mantido em mente ao discutir os benefícios finais do procedimento do procedimento do Cox-maze.


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My Special Comment by Ovidio A. García-Villarreal, MD:

I have carefully read the article by Choi et al [1]. They have found that a slight reduction in the left atrial (LA) size by means of LA reduction (50.6±8.0 mm vs. 53.6±8.9 mm; p<0.001), as a concomitant procedure with the surgical ablation for atrial fibrillation (AF), is directly linked to a decrease postoperative risk for stroke. Nevertheless, several issues of utmost importance should be analyzed in depth in respect thereof. The surgical ablation for AF should always be assumed in terms of the Cox-maze procedure (CMP) [2]. As such, the left atrial appendage (LAA) removal by means of resection or exclusion is an integral part of this surgical technique. LAA has been closely related to the thrombus formation inside the heart in patients with AF [3,4]. Such being the case, by eliminating the LAA during the CMP, the possibility of stroke is also decreased.  This has been demonstrated by Cox et al. [5]. However, the immediate goal of the CMP is the reestablishment of normal sinus rhythm, whilst preserving the transport function of both atria. In this regard, the LA size after CMP, as an expression of the LA reduction, is directly related to the final result after CMP in restoring the normal sinus rhythm [6]. The final distance between incisions or burn lines understood as the critical mass of atrial tissue available to fibrillate has much to do with the final result of the CMP [7,8].

Under these premises previously exposed, we have two extremely important factors to analyze in reference to the stroke after the CMP, viz, the final size and the critical mass of the LA, and the elimination of the LAA. Both them have already been studied and identified as crucial factors in understanding the benefit of the CMP in the current daily practice. Nonetheless, more information is on the way and comming soon by the LAAOS III trial addressing the efficacy of the LAA occlusion for stroke prevention [9].

In conclusion, if due to the LA reduction, the value of this fact in preventing the stroke risk after the CMP should be determined whilst considering the impact of the LAA removal as part of this surgical technique. 

  1. Choi W, Kim HJ, Park SY, Kim JB, Jung S-H, Lee JW. The Impact of Left Atrial Reduction during Surgical Ablation of Atrial Fibrillation. Semin Thorac Cardiovasc Surg (2021). DOI:
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  6. García-Villarreal OA. Efectividad del procedimiento de Cox-maze III a largo plazo y su relación con el tamaño posoperatorio de la aurícula izquierda. Gac Med Mex. 2019;155:590-5. doi: 10.24875/GMM.19005385. [Spanish].
  7. Garcia-Villarreal OA. eComment: Left atrial reduction in atrial fibrillation surgery: the critical mass. Interact Cardiovasc Thorac Surg. 2010;10:581. doi: 10.1510/icvts.2009.220012A.
  8. Garcia-Villarreal OA. Let's get down to the nitty-gritty in persistent atrial fibrillation: the continuous critical mass of the atria. Europace. 2019;21:1280. doi: 10.1093/europace/euz181.
  9. Whitlock R, Healey J, Vincent J, Brady K, Teoh K, Royse A,  et al. Rationale and design of the Left Atrial Appendage Occlusion Study (LAAOS) III. Ann Cardiothorac Surg. 2014;3:45-54. doi: 10.3978/j.issn.2225-319X.2013.12.06.