Minimally invasive Cox-maze procedure, beating-heart epicardial ablation, hybrid procedure and catheter ablation: a call for comparative evidence.

We read with great interest the paper by Je et al. [1] regarding minimally invasive surgical treatment for atrial fibrillation. This was a comprehensive systematic review pooling available data on the Cox-maze procedure, beating-heart epicardial ablation and hybrid procedure to compare their safety and efficacy. Based on 37 studies included in this review, Je et al. demonstrated that at 12-month follow-up, sinus rhythm restoration off antiarrhythmic drugs was 87, 72 and 71% for Cox-maze, epicardial and hybrid procedures, respectively. Similar trends were observed for sinus rhythm restoration on antiarrhythmic drugs (93, 80 and 70%, respectively). The authors concluded that minimally invasive Cox-maze procedure had the highest efficacy rates with acceptable mortality and morbidity at shortto mid-term follow-up. One limitation correctly acknowledged in this study is the lack of studies directly comparing minimally invasive endocardial Cox-maze procedures with epicardial surgical ablation for stand-alone AF. This has hindered the ability to conduct meta-analyses and produce quantitative conclusions, thus highlighting the critical need for future randomized studies comparing these minimally invasive approaches. Prior meta-analyses published on this topic have demonstrated the efficacy of surgical ablation in cardiac and mitral valve surgery [2, 3], and provided comparative results for biatrial versus left-atrial lesion sets [4], and relative efficacy and safety of different energy sources [5]. One issue that has not been addressed in this systematic review is the efficacy and safety results of minimally invasive surgical ablation versus catheter ablation for AF treatment. In recent years, there have been an increasing number of comparative studies between minimally invasive epicardial ablation versus catheter ablation, particularly in the subset of patients with failed prior catheter ablation. In the recent multicentre FAST study, Boersma et al. [6] conducted a randomized trial comparing catheter ablation (n = 63) with thoracoscopic epicardial surgical ablation (n = 61) in patients with prior failed catheter ablation or refractory AF with left atrial dilatation or hypertension. At 12-month followup, sinus restoration free from drugs was 65.6% for the surgical approach, significantly higher than 36.5% by the catheter approach. However, adverse events were significantly higher for the surgical group (34.4 vs 15.9%). These results provide optimistic data for the potential role of minimally invasive surgical ablation in the setting of patients with refractory AF with prior failed non-pharmacological intervention. However, the efficacy of thoracoscopic epicardial ablation in this setting versus other minimally invasive approaches such as Cox-maze and hybrid ablation procedure remains yet to be studied. As such, we also propose randomized studies comparing Cox-maze, epicardial and hybrid procedures in the setting of prior failed intervention to further aid in clinical decision-making to provide optimal outcomes for patients. We are grateful for Je et al. [1] for sharing their experience, extensive analyses and valuable insights. Je et al. are to be commended for taking the initiative to consolidate the available evidence, which will serve as a solid platform for future research comparing minimally invasive endocardial and epicardial ablation techniques. REFERENCES