Why doesn't the e/e' (early diastolic transmitral flow velocity/early diastolic mitral annular velocity) ratio correlate with diastolic function in the presence of valvular lesions?

Why E/e' Doesn't Correlate with Diastolic Function in Normal Hearts with Valvular Lesions

The E/e' ratio is not accurate in assessing diastolic function in normal hearts with valvular lesions because valvular pathology directly alters transmitral flow patterns independently of diastolic function, rendering this measurement unreliable in these specific clinical scenarios. 1

Physiological Basis for E/e' Limitations in Valvular Disease

Mitral Valve Disease

• In mitral stenosis, the E/e' ratio becomes invalid because:

  • The stenotic valve physically restricts transmitral flow (E velocity)
  • This restriction occurs regardless of left ventricular relaxation properties
  • IVRT and TE-e' time intervals are more reliable in this setting 1

• In mitral regurgitation with normal LVEF:

  • Increased preload from regurgitant volume artificially elevates E velocity
  • This occurs independently of actual diastolic function
  • The time interval Ar-A and IVRT/TE-e' ratio are preferred for estimating LV filling pressures 1
  • E/e' should only be considered in MR patients with depressed EF 1

Aortic Valve Disease

• In aortic regurgitation:
  • AR jet can interfere with mitral inflow velocity measurements
  • Careful sample volume positioning is required to avoid contamination
  • In severe AR, abbreviated LV filling period and premature mitral valve closure are better indicators of elevated filling pressures 1

Alternative Parameters for Valvular Heart Disease

For Mitral Stenosis

• IVRT (Isovolumic Relaxation Time) - more reliable in MS
• TE-e' (time interval between onset of mitral E velocity and annular e' velocity)
• Mitral inflow peak velocity at early and late diastole 1

For Mitral Regurgitation with Normal LVEF

• Ar-A time interval (difference between pulmonary vein A-wave reversal and mitral A-wave duration)
• IVRT/TE-e' ratio correlates well with mean PCWP and LAP 1, 2
• An IVRT/TE-e' ratio < 3 predicts PCWP > 15 mm Hg 2

For Aortic Regurgitation

• Premature closure of mitral valve
• Presence of diastolic mitral regurgitation
• LA enlargement (LA volume index > 34 mL/m²)
• TR peak velocity > 2.8 m/sec 1

Structural and Hemodynamic Considerations

Impact of Valvular Lesions on Chamber Dynamics

• Primary MR leads to LA and LV enlargement with increased chamber compliance
• This attenuates the increase in LAP that would normally occur with diastolic dysfunction
• The hemodynamic relationship that E/e' is based on becomes disrupted 1

Altered Loading Conditions

• Valvular lesions create abnormal loading conditions that affect both E and e' independently
• E velocity is preload dependent and directly affected by valvular regurgitation
• While e' is less load dependent in normal hearts, this relationship changes in valvular disease 1

Clinical Implications

Diagnostic Approach

• Recognize that E/e' has limited accuracy in patients with valvular disease
• Use alternative parameters specific to the valvular lesion present
• Incorporate multiple echocardiographic measurements rather than relying on E/e' alone

Common Pitfalls

• Overreliance on E/e' in valvular heart disease leads to misclassification of diastolic function
• Failure to recognize that normal E/e' values don't exclude elevated filling pressures in valvular disease
• Not accounting for the specific valvular lesion when interpreting diastolic parameters

Conclusion

When evaluating diastolic function in patients with valvular heart disease and normal hearts, it's essential to recognize the limitations of E/e' and use alternative parameters that have been validated for specific valvular lesions. The IVRT/TE-e' ratio is particularly valuable in mitral valve disease where E/e' is unreliable.