An implantable cardiac system has a master pacing unit and a remote satellite pacing unit. The master pacing unit is electrically coupled to a right side of a patient's heart via a lead assembly. The satellite pacing unit is a leadless device mounted on the left side of the patient's heart and is wirelessly controlled by the master pacing unit. The satellite pacing unit is affixed to the heart by one or more mounting members. The base of the satellite unit case has a gel-like material which facilitates adhesion of the pacing unit to the heart tissue. The gel-like material promotes tissue growth to hold the pacing unit in place on the heart. The gel-like material may be composed of polyvinlpyrrolidone and may contain a steroid, such as dimethyl sulfoxide (DMSO), or dexamethazone sodium phosphate.