Detailed understanding of the regional mechanical response to myocardial infarction (MI) is currently incomplete. Strain, which is most widely used for evaluating regional function, does not account for differences in loading conditions. Regional work and power, however, take load into account, but requires pressure measurement or estimation. Here, we present a noninvasive index of regional function, Regional Power Ratio (RPR), which allows comparison of the instantaneous power generated by different regions in the myocardium. We use RPR to investigate the regional dispersion of function in the MI heart, and compare to analysis of regional work.