How to assess the efficacy of catheter ablation of atrial fibrillation?

Catheterablationisanexpandingtreatmentfor atrial fibrillation (AF). But, the real outcome in terms of AF burden in the middle–long term after catheter ablation is still under evaluation. MostofthestudiesreportasuccessrateforparoxysmalAF(PAF)between60and80%,1evenif recentobservationsshowedthatthisprocedure doesnoteliminatePAFinupto56%ofpatients overanextended(.3years)follow-upperiod, despite the use of two or three ablation procedures in two-thirds of them.2 In their work, Steven et al.3 focused on AF burden after catheter ablation in a highly selected cohort of pacemaker and implantable cardioverter defibrillator carriers. The analysis of the atrial electrograms recorded by their devices was used as an index of success of AF ablation in terms of relapses either for persistent AF (PersAF) or PAF, using the following device settings: (i) arrhythmiaduration:.30 s,(ii)atrialfrequency: ,330 ms, and (iii) atrial sensitivity: 0.5 mV. According to their evaluation, AF burden dropped remarkably both for patients with PAF and with PersAF after catheter ablation. Anyway, some observations are needed: first of all, the electrogram-storage capabilities of devices are limited in terms of number/duration of arrhythmic episodes and some episodes may be lost between the follow-up visits. Secondly, according to Israel and Barold,4 since AF diagnosis needs a 12surface-lead ECG or multiple intracardiac recordings, device-detected atrial tachyarrhythmias should not be labelled AF even if device criteria are satisfied. Moreover, if we relay on the maximum detected atrial rate of .180 b.p.m., coupled with a high-atrial sensitivity (0.5 mV) (as used by Steven et al.), we could be in a condition in which AF, atrial flutter, or atrial/sinus tachycardia may overlap. These remarks, in our opinion, are important in consideration of the possible clinical implication of Steven et al.’s paper.Since AF is the most common sustained arrhythmia in the western world, showing an increasing incidence (primarily due to ageing of the population), it triggers a heavy financial burden for our health care systems,5–8related to morbidity, hospitalizations, and mortality. Since it has not yet been proved that catheter ablation’s outcomes are definitely superior than medical therapy in terms of hard end-points, and considering that economic advantages of catheter ablation with respect to medical therapy of AF emerge only after 5 years,9 it appears reasonable to restrict the candidates to AF ablation only to selected patients at higher chance of longterm maintenance of sinus rhythm. In view of these considerations, the definition of reliable indexes of successful catheter ablation of AF at long term remains to be assessed.