An active implantable medical device such as a cardiac prosthesis for the treatment of a heart failure by controlled adjustment of the atrioventricular and interventricular delays. The device provides atrioventricular and/or biventricular stimulation, a sensor delivering at least one hemodynamic parameter correlated with time intervals representative of the succession of the systolic and diastolic phases, and circuits to adjust the AV delay and/or VV delay. The device determines (12) during one cardiac cycle several parameters such as the left ventricular pre-ejection interval LPEI, the left ventricular ejection time LVET, the diastolic filling time FT and the conduction time PR. The device compares (14, 18) these parameters with at least one predetermined criterion. If a condition is met, the device readjusts (16) the AV delay and/or VV delay to maximize the ventricular filling and ejection.