The invention relates to a method for determining a plurality of action potentials in the heart having the following steps: a) recording a superficial ECG signal (31) synchronously with at least 64 channels, b) recording at least one IEGM signal (30), c) processing the superficial ECG signal by means of ICA analysis and determining the sum and position of a plurality of action potentials in the heart on the basis of the ICA analysis (32) and d) comparing the at least one IEGM signal with the plurality of action potentials (33) and correcting the sum and/or the position of at least one of the plurality of action potentials in the heart (34) on the basis of this comparison. The invention further relates to a corresponding device, a corresponding computer program product and a corresponding system.
