Background Acute pulmonary vein reconnection via epicardial fibers can be found during observation period after PV isolation, the characteristics and related factors have not been fully studied. Objective To investigate the prevalence, locations, electrogram characteristics and ablation parameters related to acute epicardial pulmonary vein reconnection (AEPVR). Methods Acute PVR was monitored during observation period after PV isolation, from which AEPVRs were mapped and distinguished from endocardial conduction gaps. The clinical, electrophysiological characteristics and lesion set parameters were compared between patients with and without PVR. So were they compared among AEPVR, gap-related reconnection, and epicardial PVR in repeat procedures. Results 56.1% acute PVR were AEPVR, which required a longer waiting period ( P<0.001) than endocardial gap. The majority of AEPVR were connections from the posterior PV antrum to the left atrial posterior wall, followed by late manifestation of intercaval bundle conduction from the right anterior carina to right atrium. AEPVR was similar to epicardial PVR in redo procedures in distribution and electrogram characteristics. Smaller atrium ( P<0.001), lower impedance drop ( P=0.039) and ablation index ( P=0.028) on the posterior wall were independently associated with presence of AEPVR, while lower inter-lesion distance ( P=0.043) was the only predictor for AEPVR in acute PVR. An integrated model containing multiple lesion set parameters had the highest predictive ability for AEPVR in ROC analysis. Conclusions Epicardial reconduction accounted for the majority of acute PVR. AEPVR was associated with anatomic characteristics and multiple ablation-related parameters, which could be explained by nondurable transmural lesion or late manifestation of non-preferential conduction.