The present invention relates to implantable medical devices (2 20) including pacemakers, cardioverters, and defibrillators and methods for such devices for selectively providing cardiac pacing to the heart of a patient. In particular, the present invention relates to improved pacing strategies for pacing hearts of patients suffering from periodical or intermittent atrio-ventricular blocks, for example, AV block or HIS block using an implantable medical device comprising: a control circuit (27) adapted to operate the device in a DDI-II mode, the DDI-II mode being an operation mode with an atrial inhibited pacing and a DDI-II mode ventricular pacing rate being lower than a predetermined base rate of a pulse circuit of the device, during periods with atrio-ventricular conduction conditions if a block in atrio-ventricular conduction is detected and at least one first switching criterion is satisfied, control the switching circuit (26) to switch from the DDI-II mode to the DDI mode and, if a block in atrio-ventricular conduction is detected and at least one second switching criterion is satisfied, control the switching circuit (26) to switch from the DDI mode to the DDD mode and wherein the control circuit (27) is adapted to control the switching circuit (26) to switch back to the DDI-II mode at satisfaction of a reinitiating criterion.Linvention concerne des dispositifs médicaux implantables (2 20) y compris des stimulateurs cardiaques, des cardioverteurs, et des défibrillateurs et des procédés destinés à de tels dispositifs pour fournir de manière sélective une stimulation cardiaque au cœur dun patient. En particulier, linvention concerne des stratégies de stimulation améliorées pour stimuler des cœurs de patient souffrant de blocage atrio-ventriculaire périodique ou intermittent, par exemple un blocage AV ou un blocage HIS utilisant un dispositif médical implantable comprenant : un circuit de commande (27) adapté pour faire fonctionner le dispositif en mode DDI-II,
