An apparatus for interpreting and displaying cardiac events of a heart connected to an implanted cardiac pacing means (2) is disclosed. The apparatus includes a telemetry head (4), at least one interpreting means (6), and a controller (14). Information telemetered from the implanted pacing means is separated into identifiable sets of data pertaining to prescribed functions, such as atrial events, ventricular events, pacemaker timed events, sensor events, and the like. Skin ECG information may also be received through another interpreting means (12) in addition to pacemaker telemetered data. Parallel processing channels are employed to process all the received data while maintaining synchronization therebetween. Memory means (16) allow the synchronized processed data to be stored for subsequent print out through a D/A converter (20) and printer (22), or to be displayed on a display monitor (26). The display monitor is controlled by display logic (24) that includes the capability to simultaneously display a plurality of selected data sets while maintaining the synchronization therebetween, and that further allows displayed events to be identified with unique markers (44, 46, 64, 66 ) or synchronized with displayed time intervals (82, 84, 92, 94) associated with the operation of the pacemaker.