How very wet this water is!

We would like to thank Drs Jacques and Philippon for their comments about our recent article¹ and for their personal contribution to the ongoing debate about surgical ablation of atrial fibrillation (AF) in patients undergoing primary mitral valve surgery.

We agree with these authors that the Cox work represents a milestone in the arrhythmias surgery and that Cox Maze III or IV procedure, the newest iteration using energy sources instead of incisions, remain the recognized gold standard for the surgical ablation of AF.

Nonetheless, standardization of these procedures and their minimally invasive evolutions is still lacking in the selection of ablation devices and appropriate lesion sets and this is contributing to existing controversies about when and how concomitant ablation of AF should be applied.

Gillinov et al.² recently published a randomized study of concomitant surgical ablation of atrial fibrillation in patients undergoing mitral valve repair or replacement. Although the investigation was not powered to detect differences in the individual or composite end points, there was, in contrast to our findings, no apparent benefit of right-atrial lesions and the antiarrhythmic effects of the biatrial Maze procedure or simple pulmonary-vein isolation in patients with persistent atrial fibrillation were similar. This confirms that we are still far from fully understanding and standardizing techniques and, for this reason, any future good large study on the matter is welcomed.

Regarding the mitral isthmus, again there is non-consensus about the inability of the bipolar clamp in creating a reliable lesion all the way to the mitral annulus because of the thickness of the AV groove in that area. Actually, what it is self-evident for us and for Drs Jacques and Philippon it is not a foregone conclusion, for instance, for Benussi et al.³ who yielded excellent clinical mid-term results performing the mitral line with bipolar radiofrequency. Moreover, even after surgical ‘cut and sew’ performed by expert surgeons the incidence of recurrent arrhythmias from the mitral annulus was not negligible.⁴

Third, also the hypothetical superior safety of cryoablation in proximity of valvular structures and coronary arteries it is not a whole truth. Indeed, Berreklouw et al.⁵ published a case of severe dysfunction of the left ventricle, on the first postoperative day, due to significant narrowing of the right and circumflex coronary arteries in the cryoablated areas.

In conclusion, especially for topics like AF ablation where it seems that you can never publish enough, we strongly believe that researchers have to prove the obvious and prove it again and again until it is necessary, to explore the known unknown avoiding the attitude of just stating the evident: ‘how very wet this water is’ (L. Frank Baum).

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