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Left ventricular ejection fraction (LVEF) has been a key variable for the diagnosis and management of heart failure over the last three decades. The British Society of Echocardiography recently updated their normal reference intervals for assessment of cardiac dimensions and function.1 They describe four categories of left ventricular function and a ‘normal’ LVEF is defined as ≥55%.
Categorisation of LVEF has become confusing with wide variation between international societies in their reporting guidelines. Categories of the American Society of Echocardiography and European Association of Cardiovascular Imaging,2 European Society of Cardiology3 and the American College of Cardiology and American Heart Association4 are summarised in figure 1. An LVEF of 40% may be described as impaired, moderately impaired, moderately abnormal or reduced. An LVEF of 50% may be described as borderline low, mildly impaired, mildly abnormal, normal or preserved.
Categories of left ventricular ejection fraction
The category of ‘normal’ LVEF is particularly troublesome. Supranormal LVEF may be a feature of pathologies such as hypertensive heart disease or hypertrophic cardiomyopathy and is associated with an adverse prognosis.5 A supranormal or hyperdynamic pattern of LV systolic function is not addressed in current guidelines. Interestingly, such patients may return to a more conventionally ‘normal’ LVEF as their heart function deteriorates.
Given this variability, it is important for echocardiogram reports to state the EF numerically. This is particularly important for heart failure specialists. Newer heart failure treatments have been proven to work at LVEF thresholds ranging from 25% to 45%, so the LVEF must be known in order to determine whether an individual patient should expect prognostic benefit from a particular device or medication. Reporting quantitative LVEF measurements also is important for patients with valvular heart disease, those receiving potentially cardiotoxic medications and in many other clinical situations. In addition, UK driving rules preclude driving below certain EFs in some conditions, again emphasising the need for a numerical EF.
It is important to be aware that measurement of LVEF may be both inaccurate and imprecise. LVEF will vary with loading conditions, valvular regurgitation and intracardiac shunts. There is significant interoperator variability in echocardiographic assessment of LVEF, even when this is measured from the same images using the same method.6 In addition, there is variability when different echocardiographic methods of LVEF assessment are employed or when different imaging modalities, such as cardiovascular MRI, are used.7
In summary, categorisation of LVEF may aide communication with patients and non-specialist colleagues but can lead to confusion. Cardiologists should look for the numerical LVEF, particularly before making important decisions about diagnosis and treatment. Finally, it is important to be aware that normal LVEF is not synonymous with normal LV systolic function and other measures, such as global longitudinal strain, may be useful in assessing impairment.8
Footnotes
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Funding The authors have not declared a specific grant for this research from any funding agency in the public, commercial or not-for-profit sectors.
Competing interests None declared.
Patient and public involvement Patients and/or the public were not involved in the design, conduct, reporting or dissemination plans of this research.
Patient consent for publication Not required.
Provenance and peer review Commissioned; internally peer reviewed.