Left Ventricular Ejection Fraction (LVEF)

The left ventricle is the heart's main pumping chamber, the one that sends blood to the body. With each beat it fills, then squeezes out a share of what it holds, and that share is the ejection fraction: a ventricle holding 120 mL that pumps out 70 mL has an ejection fraction of 58 percent. It is the single most used measure of how well the heart pumps, and the number that decides whether heart failure, if present, is the reduced or the preserved kind.

It is most often measured on a transthoracic echocardiogram, by tracing the chamber in two views at the end of filling and the end of contraction (the biplane method of discs, or Simpson's method) or from a 3D volume; some reports give a visual estimate instead, often as a range such as 55 to 60 percent. Cardiac MRI is the reference standard, and a nuclear scan or a cardiac CT can measure it too. The methods do not agree exactly, and the same scan read by two people can differ by about 5 points, so a change between two reports counts only when it is larger than that and measured the same way.

The 2022 AHA/ACC/HFSA heart failure guideline sets the bands: 40 percent and under is a reduced ejection fraction, 41 to 49 mildly reduced, and 50 and over preserved. Against the American Society of Echocardiography's reference ranges, normal runs from 52 to 72 percent in men and 54 to 74 in women; a value above that is hyperdynamic, seen with dehydration, anemia, an overactive thyroid, a leaking mitral valve or a thickened heart muscle, and worth a look rather than a reassurance. A preserved ejection fraction does not rule out heart failure, which with a stiff ventricle can occur at a normal number; the echocardiogram's measures of filling and of strain carry that part.

A reduced ejection fraction has a cause to be found: a past heart attack or narrowed coronary arteries, high blood pressure over many years, a heart muscle disease (inherited, viral, from alcohol, or from a chemotherapy such as an anthracycline or trastuzumab), a valve problem, a fast heart rhythm that has run for weeks, or a thyroid disorder. Many of these recover, and heart failure medication raises the ejection fraction in a large share of people with a reduced one, which is why the number is repeated after treatment starts. Endurance athletes can sit at the low end of normal with a large, well-trained ventricle, which is not disease.