Non- pulmonary vein sites effects of cryoballoon (CB) ablation has not clearly elucidated, yet. Herein we present, to our knowledge for the first time, a new definition method which helps to predict autonomic modification effect of CB application using atrial electrogram (EGM) characteristics and vagal responses (VRs). A 54-year-old man underwent pulmonary vein isolation (PVI) for paroxysmal atrial fibrillation. Before PVI, both atria were mapped with the aid of electroanatomical mapping system. The atrial electogram were divided 3 groups according to duration, amplitude, and number of deflections. To predict the relationship between VR and electrogram characteristics during CB application, the sites demonstrating fractionated pattern on 2.5 centimeters outside of pulmonary vein ostia were tagged on the mapping. CB application in the PV demonstrating intensive fractionated EGM sites caused a significant VR. We concluded that our case may be starting point to understand mechanism of PVI induced VR during CB application.