Early investigators assumed the normal heart emptied its blood content completely during each heartbeat. With the development of radionuclide angiography and x-ray ventriculography, work in animals and then in humans proved that a residual blood volume remains after ejection of the normal stroke volume. An influential paper from Foise and Braunwald nearly 60 years ago termed this the fraction of the LV volume ejected per beat. “The estimations of the fraction of the left ventricular end-diastolic volume that is ejected into the aorta during each cardiac cycle [provide] information that is fundamental to a hemodynamic analysis of left ventricular function.”1 We believe that this elegant work likely propagated the development of this concept and the succeeding use of the fraction of left ventricular (LV) ejection (aka LVEF) as a reliably attainable marker of cardiac pathology and clinical outcome.