Monitoring of patients undergoing surgical or endovascular ablation of AF has evolved remarkably over the last years. Current guidelines emphasize the importance of achieving complete electrical PV isolation (1), a concept that cannot be taken for granted and should not be neglected given that PV reconnection rates are as high as 70% (1).
However, despite the large number of catheter ablation procedures, only few patients undergo multidisciplinary heart team discussion for proper decision making about hybrid AF ablation. Although various ablation strategies have been proposed and implemented into clinical practice (11–15), the success rate of catheter ablation in AF patients remains low, with wide variations in ablation techniques among operators. In our study, surgical AF ablation was unsuccessful in one fifth of patients likely due to the lack of mapping and catheter ablation. Increasing evidence suggests that the hybrid approach could represent a more aggressive, but very effective treatment for such patients (16).
Given the not negligible proportion of patients experiencing failed ablations with subsequent poorer long-term clinical outcomes and quality of life, it can be speculated that hybrid surgical-catheter ablation procedures combining a minimally invasive epicardial ablation with no sternotomy and cardiopulmonary bypass with a percutaneous endocardial approach may result in improved outcomes than either procedure alone (10). However, in our study, although all patients who had undergone two-staged hybrid ablation were discharged in sinus rhythm, we could not demonstrate the superiority of the hybrid procedure over isolated surgical ablation.
The main finding of our study was a significant reduction of AF recurrence in hybrid patients in whom adjunctive BB ablation was performed. In this respect, a few considerations are relevant: (i) BB ablation in the setting of a two-staged hybrid procedure is safe and highly effective; (ii) adding this surgical ablation target, where the BB is supposed to be anatomically located, was easy to perform without a significant increase in procedural time and without requiring further blunt dissection; and (iii) BB ablation does not increase the risk for periprocedural complications.
The results obtained were better than those recorded in other centers with hybrid procedures not targeting the BB (18–21). This could be due to the fact that the BB may be involved in a number of unstable reentrant circuits, and we hypothesized that an effective lesion in the BB would prevent induction and maintenance of AF.
It is worth noting that current guidelines also suggest that catheter ablation should be reserved for patients with AF which remains symptomatic despite optimal medical therapy (1). Besides the clear indication for the need of providing practitioners and institutions with tools to measure the quality of care that AF patients receive so as to identify opportunities for improvement, the impact of lesion sets in addition to PV isolation is still uncertain. The debate remains therefore open and guidelines prompt us to improve the quality of our treatment strategies. Our study contributes in that direction by performing adjunctive BB ablation with the aim to improve the outcome. Adjunctive BB ablation in the setting of a hybrid surgical approach using minithoracotomy was safe, with an intraoperative complication rate similar to hybrid surgical ablation not targeting the BB (1% vs 3%, p = 0.42)
Prospective, registry-based data show that approximately 4–14% of patients undergoing catheter AF ablation experience complications, which means that these data do not differ from those reported with thoracoscopic surgical ablation (1). Our results show that the rate of intraoperative complications, either with or without adjunctive BB ablation, is similar to that observed with the endoscopic or thoracoscopic approach but such complications can be safely managed through a right minithoracotomy performed under direct vision. Despite being considered more invasive and burdened by higher risk, minimally invasive surgical ablation through a right minithoracotomy can also allow to address technical challenges when performing additional lesion lines (e.g. adjunctive BB ablation (9)), which seem to confer encouraging results but are not considered yet in current guidelines due to the lack of sufficient evidence.
In addition to safety aspects, a few considerations on efficacy deserve mentioning. The FAST trial randomized patients who were prone to AF catheter-ablation failure (i.e. failed previous ablation or left atrial dilation and hypertension) and reported common but substantially lower AF recurrence rates after thoracoscopic compared with catheter ablation (56% vs. 87%) at long-term follow-up (22). In our study, among the 30 patients who had undergone adjunctive BB ablation, only one (3%) had recurrent AF at a mean follow-up of 47 (45–49) months. This efficacy outcome is promising but a larger study sample from a multicenter study is required to confirm our results.
In conclusion, we believe that both isolated surgical or catheter ablation of AF are destined to provide unsatisfactory results but, at present, only few data are available for the hybrid approach. It would be interesting to understand why the high number of catheter ablation procedures is not counterbalanced by a proportionate number of hybrid procedures.