ejection fraction

noun

: the ratio of the volume of blood the heart empties during systole to the volume of blood in the heart at the end of diastole expressed as a percentage usually between 50 and 80 percent

An echocardiogram obtained 6 days after the initiation of chemotherapy showed that the ejection fraction had improved to 45%; 2 weeks later it was 66%.

—Patrick T. O'Gara et al., The New England Journal of Medicine