The invention relates to a device incorporating an endocardial acceleration (EA) sensor. A capture test circuit of the device collects a sampled EA signal and extracts a limited series of EA measurements during a duration of a predetermined temporal window opened after delivery of a pacing pulse. An indicator value based on an average of absolute values of successive EA measurements of the series of EA measurements is calculated at an end of the temporal window. The indicator value is compared to a predetermined discrimination threshold to determine the presence or absence of a capture according to whether the indicator value lies above or below the predetermined discrimination threshold. The indicator value is very robust to noise and particularly efficient in terms of computing, which reduces, in large proportions, consumption of the digital processor and thus of the capsule.