Idiopathic ventricular ectopy with left bundle branch block morphology and inferior axis commonly originates from the right ventricular outflow tract. It is very unusual for this ectopy to originate from the pulmonary artery trunk. This unusual origin can be recognized by mapping above the pulmonary valve in search of endo-cardial signals that consist of the near field low amplitude multicomponent signal preceding the far field ventricular signal. Pacemapping is often unsuccessful in this setting.