Electrogram (EGM) delineation is an increasingly important task to be performed in implantable cardiac devices such as pacemakers and defibrillators. Reliable detection and classification of EGM components might help to minimize the risk of false detections. Efforts are therefore undertaken to examine whether existing ECG delineators can be adapted for the delineation of EGMs. One issue to be solved is the low sampling rate at which EGMs are acquired. In this study we investigate performance degradation of an existing wavelet-based ECG delineator by a stepwise reduction of the sampling rate. It is shown that for signals sampled at 1 kHz, no significant performance degradation occurs in P or T wave delineation. The performance of QRS delineation is affected only at the lowest sampling rate of 62.5 Hz. For signals originally sampled at 250 Hz, no degradation in delineation performance is observed. It is concluded that the automatic delineation of ECGs can be performed at sampling rates as low as 62.5 Hz and that the low sampling rate does not significantly degrade the reliability of automatic delineation.