Abstract

Since the E/e' ratio was first described in 1997 as a noninvasive surrogate marker of mean pulmonary capillary wedge pressure, it has gained a central role in diagnostic recommendations and a supremacy in clinical use that require critical reappraisal. We review technical factors, physiological influences, and pathophysiological processes that can complicate the interpretation of E/e'. The index has been validated in certain circumstances, but its use cannot be extrapolated to other situations-such as critically ill patients or children-in which it has either been shown not to work or it has not been well validated. Meta-analyses demonstrated that E/e' is not useful for the diagnosis of HFpEF and that changes in E/e' are uninformative during diastolic stress echocardiography. A similar ratio has been applied to estimate right heart filling pressure despite insufficient evidence. As a composite index, changes in E/e' should only be interpreted with knowledge of changes in its components. Sometimes, e' alone may be as informative. Using a scoring system for diastolic function that relies on E/e', as recommended in consensus documents, leaves some patients unclassified and others in an intermediate category. Alternative methods for estimating left heart filling pressures may be more accurate, including the duration of retrograde pulmonary venous flow, or contractile deformation during atrial pump function. Using all measurements as continuous variables may demonstrate abnormal diastolic function that is missed by using the reductive index E/e' alone. With developments in diagnostic methods and clinical decision support tools, this may become easier to implement.

Highlights

  • A comprehensive assessment of diastolic function is an integral component of the complete echocardiographic examination of any patient referred with suspected heart failure, irrespective of their left ventricular (LV) systolic function

  • Diagnostic clues are provided from all modalities including cross-sectional imaging, M-mode echocardiography, and both spectral blood pool and tissue Doppler recordings

  • The LV isovolumic relaxation time (IVRT) and the mitral deceleration time (DT) both vary with the opposite biphasic pattern, since they are short in health, prolong when early diastolic relaxation is slowed, and shorten if restrictive filling develops

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Summary

| INTRODUCTION

A comprehensive assessment of diastolic function is an integral component of the complete echocardiographic examination of any patient referred with suspected heart failure, irrespective of their left ventricular (LV) systolic function. Differences between studies may be due to variations in protocol such as the timing of measurements (during or early after exercise), posture, and coexisting drug treatment, as well as to the underlying pathophysiology and the stage or severity of disease It was reported by the first proponents of the E/e’ ratio that its good correlation with PCWP was retained in patients who had a sinus tachycardia—irrespective of whether the E- and A-waves were fused (r = .86).[33] When there is complete merging of the early and atrial flow components, the assumptions about using E and e’ are no longer valid. TA B L E 1 Some technical and physiological factors that affect the utility of the E/e’ index

Technical considerations
Caribbean than in European patients Increases or remains unchanged
Findings
| CONCLUSIONS
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