The present disclosure provides systems and methods for estimating a change in an intracardiac distance between systole and diastole. A system includes a pacing electrode configured to generate a pacing pulse, a sensing electrode configured to measure an electrical artifact corresponding to the pacing pulse, and a computing device communicatively coupled to the pacing electrode and the sensing electrode, the computing device configured to determine a first amplitude of a first electrical artifact measured at the sensing electrode during systole, determine a second amplitude of a second electrical artifact measured at the sensing electrode during diastole, and calculate a mechanical index based on the first amplitude and the second amplitude, wherein the mechanical index is representative of the change in the intracardiac distance.