A device produces at least two distinct temporal components (Vbip, Vuni) from two separate endocardial electrogram (EGM) signals concurrently collected. The capture test determines a non-temporal 2D characteristic (VGM) representative of the cardiac cycle to be analyzed. The VGM is constructed using variations of one of the temporal components (Vuni) according to the other (Vbip). The devices determines the presence or absence of capture by analysis of this characteristic relative to a two dimensional domain.