Catheter ablation of atrial fibrillation (AF) became first-line therapy in patients not responding to electrical or pharmacological cardioversion. In case of paroxysmal AF, pulmonary vein isolation (PVI) aiming at complete electrical isolation is recommended due to high acute and long term success rates. However, once AF becomes persistent, ablation efficiency dramatically decreases, most likely due to advanced electrical and structural remodeling of the atria.~Some studies, most notably STAR AF II and CHASE AF suggested that additional ablation beyond PVI may not benefit patients as expected. In parallel to studies questioning additional ablation, several studies exploring novel promising techniques were published reporting positive results, e.g. high frequency source ablation, electrogram complexity guided ablation, low voltage amplitude, activation dispersion guided ablation, stepwise ablation approach, autonomic ganglia modification and techniques of identification of rotating waves and point sources to name just few.~Such contrasting studies left EP community confused with regards to the strength of reported claims and practical recommendations. Thus, presently, there is no standard approach to AF substrate ablation and specifics regarding targets and technique are left to physician discretion, most likely resulting in a delivery of unnecessary treatment and obstructing identification of valuable approaches. Thus, there is a need for further studies exploring additional ablation techniques in a rigorous, randomized studies.
Major objective is to compare the efficacy of adding additional ablation step (targeting areas of complex, continuous electrical activity in LA) beyond Re-PVI during catheter ablation of Atrial Fibrillation (AF) in patients undergoing 2nd ablation procedure.~Underlying hypothesis that in addition, to Re-PVI, an ablation step targeting areas of complex continuous activity will increase atrial arrhythmias freedom compared to Re-PVI only ablation.