Introduction: The phenomenon of intermittent retrograde conduction over an accessory pathway (AP) is very rare. Methods: We report a case of AVRT without ventricular pre-excitation and arrhythmia recorded. Stepwise decremental pacing was delivered from RV apex. When the pacing CL was shortened to 400 ms, Retrograde ventriculoatrial (V-A) Wenckebach-type block appeard with the earliest atrial activation at the ostium of CS. The S1S2 interval was first set to 450ms and then reduced by 10ms and atrial-ventricular node ERP (AVNERP) occurred at 500ms/410ms. Results: Retrograde conduction over an AP was present only during ventricular pacing with a fast pacing rate (S1S1 300ms, S1S2 500ms/290ms) and narrow QRS tachycardia was induced by atrial programmed stimulation. The AP was ablated successfully in the end. Conclusion: It is suggested that careful evaluation by EPS should be applied during baseline study, especially in the case without arrhythmia recorded.