An active implantable medical device with biventricular pacing and automatic optimization of pacing configuration. The device collects and analyzes an endocardial acceleration signal (EA), and searches for an optimal pacing configuration based upon a performance index derived from at least one value relating to one and/or the other of the two endocardial acceleration peaks (PEA I, PEA II) over a given heart cycle. Optimization search operates through a scanning of a parameter, e.g., atrio-ventricular delay, and calculation of the surface area underneath the characteristic of the peak amplitude as a function of the scanned parameter (atrioventricular delay).