A lead system, coupled to an implantable device, is configured for subcutaneous, non-intrathoracic placement relative to a patient's heart. Cardiac activity detection circuitry is coupled to the lead system and configured to detect cardiac rhythms. Disordered breathing detection circuitry is coupled to the lead system and configured to detect disordered breathing. One or both of cardiac therapy circuitry and disordered breathing therapy circuitry may be coupled to the lead system and configured to delivery therapies to treat disordered breathing. Such therapies include cardiac pacing, diaphragmatic pacing, and hypoglossal nerve stimulation therapies. A patient-external respiratory device, such as a positive airway pressure device, may be configured to deliver a disordered breathing therapy. One or more of a patient-internal drug delivery device, a patient-external drug delivery device, or a gas therapy device may be employed to treat disordered breathing.