Abstract: An implantable stimulation device (ISD) for recording and displaying cardiac episode history for analyzing efficacy of cardiac therapy. The ISD applies anti-bradycardia therapy in patients who suffer from a slow heart rate, and antitachycardia therapy in patients who experience episodes of high heart rate and/or fibrillation. The ISD detects the occurrence of these episodes, applies the necessary therapy, and stores the chronology of these events in a special memory unit. An external device may be employed to telemetrically retrieve the stored data from the ISD memory unit, and display the data in a time-line fashion for analysis by a physician. The recordation of such data provides a valuable tool for the physician to track cardiac episode history and recommend the appropriate therapy for the patient.