Cardiac catheterization is carried out using a probe having sensing electrodes disposed on a distal portion thereof, placing the sensing electrodes in galvanic contact with respective locations in an atrium of the heart, thereafter acquiring electrograms from the sensing electrodes while concurrently detecting ventricular depolarization events, generating from the electrograms a time-varying electroanatomic map showing electrical propagation in the heart, and displaying the electroanatomic map in a series of visual images, the images including an icon that visually indicates the ventricular depolarization events.