Methods and systems for monitoring a heart failure or transplant rejection status of a patient including use of a device or system to collect intramyocardial electrogram (IMEG) signals from the patient at different times automatically when a detected activity level of the patient is below a preset threshold level for a predetermined amount of time, and use of a device or system to generate a status indicator value proportional to a combination of parameters extracted from at least a portion of the collected IMEG signals. Methods and systems can also include measuring time delay values between IMEG signals collected from different locations in the patient. The IMEG signals can be collected from the right ventricular septum and the right ventricular apex of the patient or from the right and left ventricular myocardium of the patient.
