Techniques are provided for use by implantable medical devices such as pacemakers or by external systems in communication with such devices. An intracardiac electrogram (IEGM) is sensed within a patient in which the device is implanted using a cardiac signal sensing system. Cardiac events of interest such as arrhythmias, premature atrial contractions (PACs), premature ventricular contractions (PVCs) and pacemaker mediated tachycardias (PMTs) are detected within the patient using event detection systems and then portions of the IEGM representative of the events of interest are recorded in device memory. Subsequently, during an off-line or background analysis, the recorded IEGM data is retrieved and analyzed to identify false detections. In response to false detections, the cardiac signal sensing systems and/or the event detection systems of the implantable device are selectively adjusted or reprogrammed to reduce or eliminate any further false detections, including false-positives or false-negatives. Various adaptive reprogramming techniques are described.