Implantable medical device with ventricular pacing protocol including progressive conduction search

An implantable medical device operates to promote intrinsic ventricular depolarization according to a pacing protocol. The medical device operates to promote intrinsic conduction by providing elongated AV intervals or operating in an atrial based pacing mode. Conduction checks to determine if AV conduction is present are performed on a graduated or progressive scale to facilitate intrinsic emergence.