Background: The efficacy of ablation targeting low-voltage areas (LVAs) is controversial, although LVA presence is well known to be associated with AF recurrence after ablation. Atrial fibrillation (AF) substrate may not localize within LVAs. Methods and results: This observational study enrolled 405 consecutive patients who underwent an initial AF ablation procedure. The left atrial voltage map was obtained after pulmonary vein isolation. LVAs were defined as areas with voltage < 0.5 mV. To estimate whole atrial electrophysiological degeneration, mean regional voltage at each of 6 regions and left atrial total conduction velocity were measured. LVAs existed in 143 of 405 (35.3%) patients. Patients with LVAs demonstrated lower mean regional voltages throughout all 6 regions than those without LVAs (1.3 [1.8, 0.8] vs. 0.6 [1.0, 0.2] for anterior wall, p<0.001). On the other hand, left atrial conduction velocity was lower in patients with LVAs than in those without (0.89 [1.01, 0.74] vs. 0.93 [1.03, 0.87] m/s, p<0.001). Multivariate analysis revealed that low left atrial total conduction velocity and a higher number of regions with mean voltage reduction were independently associated with AF recurrence, although LVA presence was not. Conclusion: Patients with localized left atrial LVAs were characterized by whole left atrial electrophysiological degeneration as assessed by mean regional voltage and conduction velocity. In addition, whole left atrial electrophysiological degeneration parameters were well associated with AF recurrence.