Unanswered Question: Which Lesion Set Is Best in Thoracoscopic Atrial Fibrillation Ablation?

Objective: Pulmonary vein isolation (PVI) in minimally invasive atrial fibrillation (AF) ablation surgery is highly effective. Controversy exists, however, about the merit of extending the lesion set. The dilemma is not only the balance between increases of invasiveness versus potential therapeutic advantage. It is also our inability to truly map for gaps and non-transmurality of surgical or preexisting interventional ablation lines. We report the outcomes of our closed chest, beating heart AF ablation as the applied lesion set has evolved.

Methods: Between 2010 and August 2015, 57 patients (age 62 ± 9.5, 0.35 female) underwent totally thoracoscopic ablation (TTA) at our institution. Indications were symptomatic, paroxysmal (n = 24) or (long-standing) persistent (n = 33) AF. Fifty patients had previous failed catheter ablation. Bilateral PVI by bipolar radiofrequency (RF) (n = 52) or cryothermy (n = 5) ablation and left atrial appendage (LAA) excision was uniformly applied in the majority of the procedures. Follow up for most patients was by insertable loop recorders or pacemakers.

Results: There were no perioperative or late mortality, and all patients were discharged in good condition. Nine patients were converted to sternotomy, predominantly at the beginning of our experience and with changes in the ablation protocol. While the first 16 patients were treated with PVI and LAA excision only, the following 27 patients additionally received a box lesion. Procedural success, defined as AF burden < 0.5% in the last 2 months of follow-up, remained similar (82 vs. 78%), although 8 patients with the box lesion had had interventional ablation for postoperative atrial flutter. The latest development in the remaining 14 patients included a line from the right PVI to the fibrous trigone between aortic and mitral valves, and we observed no left atrial flutter ever since. AF burden, however, was not improved (78%).

Conclusion: AF burden is markedly reduced after TTA, yet the procedural success is mainly a function of bilateral PVI. The extended lesion set did not add to these results, although epicardial ablation of the LA backwall and roof is a major distinctive feature as compared with interventional ablation. Future developments must focus on surgical lines that are gapless and fully transmural.