Occidental lifestyle including lack of physical activity, are related to risk of developing heart diseases. ATP has a central role in understanding cardiac metabolism. Thus, this study was carried out to discuss aerobic cardiac metabolism, with most of the energy provided by oxidative phosphorylation. The ATP produced by this pathway is essentially used for contraction in non-pathological conditions. In addition, situations are discussed on the glycolytic pathway to produce ATP under pathological conditions. Thus, in some cardiomyopathies, the manipulation of the metabolic status of the heart represents an attractive alternative for the prevention of later complications.