A method for performing a medical procedure includes holding a non-linear dependence between the duration of a given phase within a cardiac cycle and a respective heartbeat rate. First and second image sequences of the dynamic activity of the heart of a patient, acquired at respective different first and second heartbeat rates of the heart, are received. Synchronization between the first and second image sequences is performed based on the non-linear dependence, on the first and second heartbeat rates, and on a given common heartbeat rate. The first and second image sequences are played in synchronization with the common heartbeat rate.