An implantable medical device for electrically stimulating the heart to beat generally includes a processor, a plurality of electrodes, a sense amplifier, a pair of comparators, inner and outer target logic units, and pulse generator. The processor controls the magnitudes of inner and outer target reference signals which are generated by the inner and outer target logic units, respectively. The outer target is adjusted to be approximately equal to the peak amplitude of the cardiac signal. The processor stores representations of the outer target reference in memory. Alternatively or additionally, the processor computes a histogram of the relative or absolute number of cardiac cycles that occur over a given period of time for each outer target setting. The processor can be directed to retrieve the outer target representations and/or the histogram from memory and transmit that information to an external programmer for use by a physician.