OE-039 Critical Ablation Site for Maintenance of Atrial Fibrillation During Electrogram-guided Antrum-Pulmonary Vein Isolation-Fast Fourier Transform Analysis of Atrial Fibrillation(Arrhythmia, therapy-1 (A) OE7,Oral Presentation (English),The 70th Anniversary Annual Scientific Meeting of the Japanese Circulation Society)