34 years old man with frequent palpitations referred to our center. Three standard diagnostic catheters were introduced through left and right femoral veins and placed in right atrium, right ventricle and coronary sinus positions. A narrow complex tachycardia with long RP-short PR could be initiated after extarstimulation from HRA following an AV nodal jump. The earliest retrograde atrial activation was recorded from His bundle position. RV apical pacing showed decremental with earliest atrial activation in His area, although no fused V-A potential was recorded in either CS or His position. His synchronous pacing from RV apex failed to advance or reset the arrhythmia. Morady maneuver by RV overdrive pacing repeatedly terminated the tachycardia. Mapping was initiated from His region and extended to all anticipated areas from parahisian region to tricuspid annulus, posteroseptal TV ring and CS. The construction of RA activation map failed to reveal earliest activation site. Mapping catheter was introduced through femoral artery and advanced to the left ventricle. At anteroseptal mitral annulus corresponding to Aorto-Mitral continuity, we recorded the earliest retrograde atrial activation (A-distal CS =50 ms). RF energy (30 W) was delivered using an irrigate tip catheter during tachycardia and resulted in termination of tachycardia immediately.