Background: Pulmonary vein potentials (PVPs) followed by left atrium (LA) potential indicate electrical connection between LA and PV, and represent depolarization of muscular fascicles within PV myocardial sleeve. The PVPs are demonstrated to have some decremental conduction properties in response to extrastimulation (ES). However, it is not well defined whether the response of PVPs to ES is different between arrhythmogenic PV and bystander PVs in patients with paroxysmal atrial fibrillation (PAF). Methods: In 26 patients with PAF referred for catheter ablation and performed programmed stimulation with a single atrial ES, 10 patients (M:F=7:3, 55.6짹14.1 years old) showing spontaneous AF initiated by ectopic beats originating from PVs were studied. Bipolar electrograms were recorded with a decapolar Lasso catheter positioned sequentially within the left superior, left inferior, right superior, and right inferior PVs, at each ostium. 18 PVs were divided into 2 groups, 10 arrhythmogenic vs. 8 non-arrhythmogenic PVs. Maximum (LA-PVmax) and minimum (LA-PVmin) interval of LA to PVp were measured during sinus rhythm, S1, and S2 obtained by pacing at distal coronary sinus (CS) for left PVs and at proximal CS for right PVs. Results: ES resulted in greater separation of LA to PVP in arrhythmogenic PVs. LA-PVmax, ��(LA-PV)max-min after S2 were significantly longer (47짹5.0 vs. 32.5짹4.3 ms, p=0.034 and 31.2짹3.7 vs. 16.6짹3.3 ms, p=0.016, respectively) in arrhythmogenic PV. The difference between ��(LA-PV)max-min after S2 and ��(LA-PV)max-min after S1 was also significantly greater in arrhythmogenic PV (12.0짹3.3 vs. 2.3짹0.8 ms, p=0.009). Conclusions: Arrhythmogenic PVs had a greater degree of decremental conduction property than that of other PVs, and showed heterogeneity in conduction property. Assessment of the response of PVPs to extrastimulation can facilitate to identify arrhythmogenic PVs, which could be good targets for preferential catheter ablation.