E/e’ Average Calculator

E/e' Ratio: Explanation and Clinical Context The E over e prime ratio is one of the most widely used echocardiographic indices to estimate left ventricular filling pressure. The E wave represents early diastolic transmitral flow velocity which increases when the left atrial pressure rises. The e prime velocity is measured at the mitral annulus and reflects the intrinsic rate of myocardial relaxation.

Since e prime decreases in impaired relaxation, a high E over e prime ratio indicates that transmitral flow is disproportionately elevated relative to the relaxation capacity of the ventricle. As a result, the ratio serves as a surrogate marker of elevated left ventricular filling pressure. The average e prime value obtained from both the septal and lateral mitral annulus is recommended because it improves the accuracy and reduces the variability that may be encountered when a single site is used.

An E over e prime ratio below fourteen is generally considered normal in adults. Values of fourteen or higher suggest increased filling pressures. This threshold is supported across major clinical guidelines and has been validated in diverse populations including patients with heart failure, hypertensive heart disease, and ischemic cardiomyopathy.

Clinically, the E over e prime ratio plays a central role in the evaluation of diastolic function. It is particularly useful in patients with preserved ejection fraction where symptoms may be present despite normal systolic performance. When interpreted together with additional parameters such as mitral inflow pattern, pulmonary vein flow, tricuspid regurgitation velocity, and left atrial volume index, it contributes to the comprehensive classification of diastolic dysfunction severity.

This parameter is also relevant during stress echocardiography. An abnormal increase in E over e prime during exercise suggests impaired left ventricular compliance and can help confirm the diagnosis of heart failure with preserved ejection fraction. In acute care settings, the ratio assists clinicians in differentiating cardiac from non cardiac causes of dyspnea.

The interpretation of E over e prime should always be integrated with the entire clinical context. Factors such as significant mitral annular calcification, mitral stenosis, prosthetic valves, regional wall motion abnormalities, or tachycardia can affect the accuracy of measurements. When these limitations are present, alternative indices or invasive hemodynamic assessment may be required.

Reference Nagueh SF et al. Recommendations for the Evaluation of Left Ventricular Diastolic Function by Echocardiography. Journal of the American Society of Echocardiography.

2016. Ommen SR et al. Clinical Utility of Doppler Echocardiography and Tissue Doppler Imaging in the Estimation of Left Ventricular Filling Pressures.

Circulation. 2000. Marwick TH et al.

Diastolic Stress Testing. JACC Cardiovascular Imaging. 2017.

Yancy CW et al. 2022 AHA Scientific Statement on Heart Failure. American Heart Association.