Novel strategy of catheter ablation for persistent atrial fibrillation-Ｈow to optimize extra-PV substrate modification

Electrical pulmonary vein (PV) isolation (PVI) has been regarded as a corner stone for the treatment of paroxysmal atrial fibrillation (AF), and its efficacy also has been investigated by many investigators. After multiple catheter ablation sessions for PVI, more than 90% of paroxysmal AF patients have been free from AF recurrences. In contrast to that, persistent AF seems to require various kinds of therapeutic modalities to ablate the following arrhythmogenic substrates that exhibit findings such as low voltage areas, complex fractionated atrial electrograms, and dominant frequencies in addition to the PVI. Moreover, the superior vena cava, atrial septum, left atrial posterior wall, Marshall vein, and right atrial tissue such as the crista terminalis and cavo-tricuspid annulus have also been regarded as target sites of catheter ablation for the sake of treating persistent AF. However, the issue of which catheter ablation therapeutic modality for these “non-PV” targets of persistent AF will be optimal has not yet been clarified up to now. The success rate of catheter ablation of persistent AF has not been satisfactory presumably due to the advanced electrical remodeling, fibrosis, and degeneration of the atrial tissue. A hybrid treatment with antiarrhythmic agents and catheter ablation has also been advocated to treat persistent AF. The blanking period after a PVI for AF ablation between paroxysmal and persistent AF might have different clinical implications and impacts. In this symposium, we would like to discuss these issues by reviewing the previous work and debating the future direction with regard to how to perform catheter ablation of persistent AF.