An active implantable medical device, preferably a device for pacing, resynchronization, defibrillation and/or cardioversion of a patient, that includes functionality that assists in the diagnosis of the patient's clinical status. This devices comprises circuits (10, 12) for measuring one physiologic parameter, preferably minute ventilation (VE), and circuits (14, 16) for measuring a physical parameter, preferably acceleration (G), control logic (18) for discriminating between activity and rest phases of the patient, and analysis circuits (20-28), to process and combine these signals and memorize (store in memory) the obtained results in the form of a data history. The analysis will establish characteristics providing, for successive dates, representative values, for a given period of time, of the physical signal and physiologic signal during activity phases of the patient, and/or of the physiologic signal during rest phases. These circuits search for remarkable dates for each of the characteristics and allocate specific indices of clinical status respective to each of the periods comprised between the remarkable dates, then combined the specific thus obtained into one single composite index.