The possible correlations between unipolar endocardial electrogram amplitudes and voltage threshold stimulation were tested with electrodes having metallic tips of two different areas. The threshold measurements were always studied with the same pulse characteristics. The data were analyzed through five mathematical functions (linear, exponential, potential, hyperbola and translate hyperbola). The results show a significant correlation, mainly by hyperbolic and exponential functions. Consequently, we could deduce a parameter value since we already knew the other one. This was possible not only during the first implantation, but also later on.