Nakatani Y, et al. - In this study including consecutive patients (n=126) who were ablated for persistent and long-standing persistent atrial fibrillation (AF), the parameters related to P-wave amplitude (PWA) were assessed for their predictive efficacies for recurrence of AF following catheter ablation. Follow-up of 32 ± 15 months revealed no recurrence of atrial fibrillation in 87 patients (69%). Patients with AF recurrence vs those without exhibited lower maximum PWA, mean PWA, and P-wave vector magnitude. P-wave vector magnitude was identified as a predictor of AF recurrence post-catheter ablation in patients with persistent AF. In patients with P-wave vector magnitude higher and lower than 0.13 mV, the estimated atrial fibrillation freedom rates were 93% and 57%, respectively. A weak correlation of P-wave vector magnitude with left atrial dimension was also shown.