EComment. Left atrial appendage: an underestimated component of surgery for atrial fibrillation

Abstract

We have read with great interest the manuscript by Bakker et al. [1], in which they share their surgical experience with the modified maze procedure as concomitant surgery and define risk factors for recurrent atrial fibrillation. It is a well-designed retrospective cohort study, but a few issues have to be discussed. 66.9% of patients had a left atrial appendage (LAA) amputation and 10.7% of patients had a bi-auricular amputation in the study cohort. There were 2 patients, who had a stroke even in early postoperative course (<30 days). It is well established that LAA amputation is an important component of the Cox-maze procedure. The role of LAA has been increasingly recognized in the initiation and maintenance of AF. Moreover, LAA amputation not only lowers the risk of embolic events postoperatively, but also lowers risk of recurrent atrial fibrillation. Recent papers have shown that LAA is an underrecognized trigger site of AF and may be an important area causing recurrent AF after ablation [2]. For that reason, it would be wise to perform LAA amputation as an integral part of Cox-maze procedure. One obstacle for this may be the physiological role of LAA. It is known that LAA has role in supporting cardiac output and regulation of blood pressure, and modulating thirst and hypercoagulability. In humans, it has been shown that atrial natriuretic peptide (ANP) and brain natriuretic peptide concentrations, levels of von Willebrand factor, D-dimer, and thrombin-antithrombin III complex increase with LAA dysfunction. However, there were no alterations in haemodynamics and coagulation in patients with amputated LAAs [3]. In terms of the right atrial appendage (RAA), there is currently no strong evidence for performing an RAA amputation during arrhythmia surgery except in patients with thrombi in the RAA (rare, when compared to LAA) [4]. Moreover, it is suggested that preservation of the RAA attenuated the reduction in plasma ANP levels after the maze procedure. So, the increased plasma ANP levels may have protective role in detrimental haemodynamic consequences after surgery [5]. As a result, surgeons must amputate LAA routinely in the surgical treatment of AF, whereas RAA amputation must be amputated occasionally with strict indications. Conflict of interest: none declared