The present disclosure relates to an intracardiac pacemaker device (1), comprising a housing (10) that is configured to be implanted entirely within a ventricle (V) of a heart (H), an electronic module (20) for generating pacing pulses, a battery (30) for supplying energy to the electronic module (20), an elongated lead extension (40) protruding from the housing (10), at least a first electrode (41) arranged on the elongated lead extension (40), and a pacing electrode (11) and a return electrode (12) for applying said pacing pulses to cardiac tissue, wherein the pacing electrode (11) is arranged on the housing (10). The electronic module (20) is electrically coupled to the pacing electrode (11) via the housing (10), and wherein the electronic module (20) is configured to carry out measurements of electrical activity via the at least one first electrode (41) of the elongated lead extension (40).
