Results: We studied surface electrocardiograms during tachycardia of 23 successfully ablated patients with idiopathic ventricular outflow tract: 6 patients (26%) from the free wall of RVOT have QRS duration time > 140 ms, RR' or R'R waveform at DII, DIII leads and contrary to electrocardiogram features of 15 patients (65.2%) from septal RVOT.