The myocardial contraction fraction (MCF) is based on the principle that the myocardium is nearly incompressible and does not change volume significantly from end-diastole to end-systole. By indexing the stroke volume to the myocardial volume, the MCF is an index of the volumetric shortening of the myocardium that is independent of chamber size and geometry. The MCF, while analogous to EF in terms of being unitless and free of the need for indexation for body size, offers several theoretical advantages including expressing the strain relationship only in terms of that which shortens, namely the myocardium, thereby providing an ability to distinguish pathologic from physiologic hypertrophy.