E/e' Ratio in Clinical Practice

Introduction to E/e' Ratio

The E/e' ratio is a noninvasive echocardiographic parameter that estimates left ventricular filling pressures by dividing the early diastolic transmitral flow velocity (E) by the early diastolic mitral annular velocity (e') 1

E velocity represents the early diastolic transmitral flow measured by pulsed-wave Doppler, reflecting the pressure gradient between the left atrium and left ventricle during early diastole, and is influenced by left ventricular relaxation, restoring forces, and left atrial pressure at the time of mitral valve opening 2
e' velocity is the early diastolic mitral annular velocity measured by tissue Doppler imaging (TDI), primarily reflecting left ventricular myocardial relaxation with minimal influence from loading conditions when relaxation is impaired, and should be measured at both the septal and lateral mitral annulus positions 1, 2

For average E/e' ratio, values <8 indicate normal left ventricular filling pressures, while values >14 have high specificity for elevated left ventricular filling pressures, and values between 8-14 are considered indeterminate and require integration with additional echocardiographic parameters 2
An E/e' ratio >15 definitively indicates elevated filling pressures and persistent congestion 2

The E/e' ratio serves as a critical tool for distinguishing heart failure with preserved ejection fraction (HFpEF) from other causes of dyspnea in patients with hypertension, diabetes, and heart failure symptoms, with the presence of ≥2 abnormal diastolic measurements (including elevated E/e') increasing diagnostic confidence for HFpEF 3
For hypertensive patients, an abnormally increased E/e' ratio is suggestive of primary cardiac events and helps identify hypertension-mediated cardiac damage 4

In cardiac amyloidosis, E/e' ratios are typically markedly elevated (>14), often accompanied by a restrictive mitral inflow pattern (E/A ratio >2.5), deceleration time <150 msec, and severely reduced e' velocities (3-4 cm/sec) 1
Speckle tracking echocardiography showing apical sparing of longitudinal strain on polar plot is a characteristic phenotype that helps distinguish cardiac amyloidosis from other causes of left ventricular hypertrophy 1, 4

The correlation between E/e' and invasively measured filling pressures is only modest (pooled correlation coefficient r=0.56) even in well-selected HFpEF populations 6, 2
E/e' has limited accuracy in several important clinical scenarios, including heavy mitral annular calcification, mitral valve disease, pericardial disease, regional wall motion abnormalities from coronary artery disease, and atrial fibrillation 2

Calculate the average E/e' by measuring e' at both septal and lateral positions and averaging the two values, providing optimal assessment of global diastolic function 2
Normal reference values are septal e' ≥7 cm/s and lateral e' ≥10 cm/s, and E/e' should always be integrated with other echocardiographic parameters rather than relying on this single measurement in isolation 2, 1, 3