From the Guidelines
The E/e' ratio in cardiac echocardiography is a crucial measurement for estimating left ventricular filling pressures and assessing diastolic function, with values greater than 15 indicating elevated left ventricular filling pressures and diastolic dysfunction, as supported by the most recent and highest quality study 1.
Definition and Interpretation
The E/e' ratio compares the early mitral inflow velocity (E wave) measured by pulsed-wave Doppler with the early diastolic mitral annular velocity (e') measured by tissue Doppler imaging.
- A normal E/e' ratio is generally less than 8,
- values between 8-15 suggest possible diastolic dysfunction,
- and values greater than 15 strongly indicate elevated left ventricular filling pressures and diastolic dysfunction, as stated in the guidelines 1. The ratio is particularly useful because it combines information about both left ventricular relaxation (represented by e') and the driving pressure for filling (represented by E), making it less load-dependent than other echocardiographic parameters.
Clinical Application
When interpreting the E/e' ratio, it's essential to consider both septal and lateral e' velocities, as they can differ.
- Some cardiologists use an average of these measurements for more accurate assessment.
- The E/e' ratio should always be interpreted in the clinical context and alongside other echocardiographic parameters of diastolic function for comprehensive evaluation of cardiac function, as recommended by the American Society of Echocardiography and the European Association of Cardiovascular Imaging 1. The 2016 ESC guidelines and the 2016 ASE/EACVI recommendations emphasize the importance of an integrated assessment of multiple echocardiographic markers, including the E/e' ratio, for diagnosing heart failure with preserved ejection fraction (HFpEF) and estimating left ventricular filling pressures 1.
Key Points
- The E/e' ratio is a valuable tool for assessing diastolic function and estimating left ventricular filling pressures.
- Values greater than 15 indicate elevated left ventricular filling pressures and diastolic dysfunction.
- The ratio should be interpreted in the clinical context and alongside other echocardiographic parameters.
- An integrated assessment of multiple echocardiographic markers is essential for diagnosing HFpEF and estimating left ventricular filling pressures, as supported by the guidelines and recommendations 1.
From the Research
Definition of E/e' Ratio
- The E/e' ratio is a parameter used in cardiac echocardiography to assess diastolic function and estimate left ventricular (LV) filling pressures 2, 3, 4, 5.
- It is calculated by dividing the early diastolic transmitral flow velocity (E) by the early diastolic mitral annular tissue velocity (e') 2, 3, 4.
Clinical Significance
- A high E/e' ratio is indicative of increased LV filling pressures and diastolic dysfunction 2, 3, 4.
- The E/e' ratio can be used to diagnose diastolic heart failure and guide patient management 4, 5.
- The ratio can also be used to assess the effectiveness of treatment and monitor disease progression 2, 3.
Interpretation
- The E/e' ratio should be interpreted in the context of a patient's age and the rest of the echocardiogram to describe diastolic function 2.
- A combined assessment of the E/e' ratio and transmitral flow pattern can provide a more comprehensive understanding of cardiac function 3.
- The E/e' ratio can be used in conjunction with other parameters, such as the left ventricular ejection fraction, to inform decisions regarding patient care 5.