When does the E/e' index not work? The pitfalls of oversimplifying diastolic function

Area of Science:

• Cardiology
• Echocardiography
• Diastolic Function

Background:

• The E/e' ratio, a noninvasive marker for pulmonary capillary wedge pressure, is widely used but requires critical evaluation.
• Its clinical application has expanded significantly since its 1997 description.
• Technical, physiological, and pathophysiological factors can impact E/e' interpretation.

Purpose of the Study:

• To critically reappraise the clinical utility and limitations of the E/e' ratio.
• To explore factors affecting E/e' interpretation and its applicability in diverse patient groups.
• To discuss alternative methods for assessing diastolic function and filling pressures.

Main Methods:

• Review of technical factors, physiological influences, and pathophysiological processes affecting E/e'.
• Analysis of meta-analyses regarding E/e' utility in heart failure with preserved ejection fraction (HFpEF) and diastolic stress echocardiography.
• Comparison of E/e' with alternative methods for estimating cardiac filling pressures.

Main Results:

• E/e' validation is limited to specific circumstances and cannot be extrapolated to all patient populations, including critically ill patients or children.
• Meta-analyses indicate E/e' is not useful for diagnosing HFpEF or assessing diastolic function during stress echocardiography.
• Evidence for using E/e' to estimate right heart filling pressure is insufficient.
• E/e' alone can be uninformative, and alternative methods may offer greater accuracy.

Conclusions:

• The widespread clinical reliance on the E/e' ratio warrants critical reappraisal due to its limitations and lack of universal applicability.
• Alternative echocardiographic methods and continuous variable analysis may provide more accurate assessments of diastolic function and filling pressures.
• Future developments in diagnostic tools may facilitate the implementation of more comprehensive diastolic function assessments.