Does the current knowledge suggest a more aggressive approach?
As the ablative techniques and the technology in the field evolve, how to perform isolation of LPW remains a very debatable, controversial issue. Studies in which creation of linear lesions as to isolate LPW have been employed, have produced different results (1,9). In this respect, Tamborero et al reported that LPWI provided by linear lesions does not improve the clinical outcome of circumferential PVI. They have provided LPWI by performing a roof line and a floor line (two lines connecting the contralateral PV encircling lesions). In addition, mitral isthmus ablation was performed in all patients. In the study by Sayuri et al, the same pattern of lesions has been proposed, but several issues need to be addressed when linear lesions in the LA posterior wall are taken in account. There is an inherent technical difficulty to provide a successful electrical LPW isolation by a set of linear radiofrequency lesions, due to the complex anatomical architecture of the atrial musculature. Again, even if conduction block along the lines is achieved during the procedure, one cannot rule out the occurrence of gaps over time and, thus dormant conduction may take place during the follow-up. In fact, in the study by Sayuri et al, reconnection of posterior wall is reported in 65% of patients after the second procedure. Nearly 70% of patients in the study by Tamborero et al had reconnection of the roof line or recurrence of electrical activity within the LPW that led to AF relapses. Therefore, it is conceivable that there are still doubts about the durability of linear lesions in the LPW for the promotion of “durable box lesion”. Needless to say that all these attempts of LPWI without proven of effective isolation of the target structure make difficult to properly assess the true impact of this ablative approach on clinical outcome at follow-up. This does not mean that isolation of LPW is not worth performing. Indeed, surgical isolation of the LPW has been proved to be durable and effective in improving the freedom from atrial arrhythmias in patients with any kind of clinical presentations of AF (10). In this regards, the effectiveness of LPWI has been recently highlighted by hybrid approach, in which surgeon and electrophysiologist are side-by-side as to achieve the best clinical results in patients with persistent AF (11). In particular, the hybrid Convergent procedure as a minimally invasive closed-chest procedure performed on the beating heart that combines epicardial RF ablation—focused on the LPW— followed by complementary endocardial catheter ablation has been proved to significantly reduce the AF burden and improve the clinical outcome of patients with persistent and long-persistent AF. In detail, the epicardial component seeks to debulk as much of the LPW as can be accessed, principally limited by the oblique sinus. Posterior segments of the PV ostia/antra may also be reached and ablated in most cases. The endocardial component supplements the epicardial lesions around the pericardial reflections and any incompletely ablated LPW areas and addresses any remaining gaps between the PV and LPW lesion sets (including anterior segments), ensuring PV electrical isolation. The importance to deliver epicardial and endocardial lesions set is mainly dictated to overcome the degree of disparity between the endocardium and epicardium that can induce and sustain fibrillatory activity. Therefore, the overlap between the epicardial and endocardial lesion sets is preferred to avoid arrhythmogenic gaps and ensure transmurality. Single- and multicenter studies have reported freedom from AF or any atrial tachyarrhythmia to be 66%–95% at 1 year after the hybrid Convergent procedure, with 52%–81% arrhythmia-free without antiarrhythmic drugs (see 7 Malaki) A report of 81% of patients in SR after 4 years suggests favorable durability but additional long-term data are necessary(see 23 Malaki). These results are especially encouraging since the procedure has been frequently used in the most refractory patient populations.