Pulmonary vein reconnections or substrate in the left atrium: what is the reason for atrial fibrillation recurrences? A dialogue on a pressing clinical situation.

Pulmonary vein isolation (PVI) has long been held as the cornerstone for atrial fibrillation (AF) ablation. There are patients who do not have successful AF ablations though, especially among those with persistent AF. At the same time, the evidence suggests that ablating beyond the pulmonary veins does not improve success rates. Two possibilities for the incomplete success rates from the procedure are discussed: that more attention needs to be paid to PVI, optimizing delivery of durable, transmural lesions; or alternatively, shifting the focus away from just PVI and addressing the left atrial substrate itself. These two approaches are likely complementary though, and high-density mapping may offer us the ability to undertake them more effectively. The conclusion from this dialogue is that AF is a heterogenous disease and key is to recognize this heterogeneity and respond to it, rather than have a standardized, dogmatic approach. Durable PVI is clearly an important determinant of success but concurrently, we would suggest we need to go beyond this where appropriate to maximize success rates. Clearly the challenge is defining which patients this is appropriate for and how best to do this. Consequently, rather than being 'the' cornerstone of AF ablation, it is more appropriate to consider PVI as 'a' cornerstone of the procedure going forwards and high-density mapping may be the key to optimizing both aspect of the procedure and in so doing improve long term success rates.