Safety and Efficacy of Stand-Alone and Hybrid Thoracoscopic Atrial Fibrillation Ablation

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1. This is an honest paper that exemplifies a field in evolution. Where will surgeons fit in the treatment of standalone AF patients in the modern (PFA) era? Bipolar RF clamps, as used in this paper, have the same failure mode as all ablation technologies (including PFA): epicardial fat tissue – common in late-stage AF, especially present in the postero-inferior LA and impedes all ablation energies. Despite what looks like acute success (isolation), recurrence and electrical reconnections happen with a certain frequency. In essence, ablation/electrical isolation of the posterior left atrium (PVI + PWI: a ‘box’ lesion) is only really ‘guaranteed’ to be complete with the cut-and-sew technique. Any other method used to create a box lesion will be associated with a range of electrical voltage that continues to escape the box compared to when there was no box at all.
   This multicenter registry data was generated before and during the PFA transition era, and what was offered in MIS thoracoscopic and hybrid ablation and other approaches like Convergent sounded very useful back then: a much better box lesion compared with what could safely be made using pre-PFA tech. Of course, from the surgeons’ perspective, a box lesion is merely the base lesion of a meaningful left-sided ablation. Regardless, we are in a different situation now and have to offer something better than a box lesion that still leaks electricity (PFA also creates a box lesion that still leaks some electricity).
   Even when surgeons make a ‘really good box lesion’ with an opened left atrium, we add a mitral isthmus lesion – we would never expect a box lesion alone to be ‘enough’ in late-stage or structural lesion-associated AF. But – we cannot give anyone the impression that a catheter-based MI lesion is comparable to a surgical MI lesion in any meaningful way. EPs make their MI line closer to P1/lateral commissure and do not accomplish the most important thing: en bloc ablation of the MI, the coronary sinus and all its associated fat tissue while connecting to the mitral annulus fibrous ring to the box lesion. Catheter-based MI ablation begs epicardial electrical reconnections and also leaves the entire floor of the left atrium available to sustain AF voltage that continues to leak from the (allegedly) boxed-in posterior wall. Interestingly, PFA is not a solution for MI ablation based on published studies with 3-month remapping. EPs have adjunctive interventions they can employ to help their MI line ‘work better’ – vein of Marshall ablation and internal CS ablation, but these are time consuming and longer term recurrence is still an issue.
   Adding epicardial LAAO (low rates in this study ~20%) is important; whether or not there will be an AF-reduction benefit with epicardial LAAO is still controversial., but stroke reduction benefit without device leaks is useful, at least for now. Finally – if surgeons want their open or MIS ablation offering to be substantially better than what you can get with modern PFA-CA , we need to provide a surgical MI lesion in the P2-medial vicinity that is transmural, connects to the box lesion and includes en bloc ablation of the CS and all of the fat in the isthmus. We know how to do this with standard open-atrium techniques, and best practices (i.e. internal/external MI cryoablation) are important for reproducibility. Cut-and-sew level effectiveness and durability is the goal. The next trick is to do it without having to open the left atrium.

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