System for filtering cardiac signals. The system includes: cardiac terminals (10a-d) adapted to collect cardiac electrophysiological potentials from a plurality of cardiac electrodes (1a-d) placed at respective cardiac locations in or on an individual (99) and a processor device (40) adapted to process one or more input signals, which are based on the collected electrophysiological potential(s). The processing includes running an adaptive filter algorithm on one or more signals based on the input signals. The adaptive filter algorithm is arranged to calculate estimated noise component(s) of the signals and arranged to subtract the estimated noise component(s) from the signals. In this way a cardiac signal is derived where the noise has been significantly reduced.