Power saving communication techniques for communicating in a medical device system. One example medical device system may be for delivering electrical stimulation therapy to a heart of a patient, and may include a first implantable medical device implanted in a first chamber of the heart and configured to determine one or more parameters, a medical device physically spaced from and communicatively coupled to the first implantable medical device, the medical device configured to deliver electrical stimulation therapy to the heart of the patient, wherein the first implantable medical device is further configured to: compare a value of a first determined parameter to a first threshold； if the value of the first determined parameter passed the first threshold, communicate a first indication to the medical device； and if the value of the first determined parameter has not passed the first threshold, not communicating the first indication to the medical device.
