What is a Reversed E/A Ratio on Echocardiogram?
A reversed E/A ratio (E/A < 1) on echocardiogram indicates impaired left ventricular relaxation (Grade I diastolic dysfunction) when the E velocity is ≤50 cm/sec, representing the earliest stage of diastolic dysfunction where left atrial pressure is typically normal or low. 1
Understanding the E/A Ratio
The E/A ratio compares two components of mitral inflow during diastole:
- E wave: Early diastolic filling velocity (passive filling as the LV relaxes)
- A wave: Late diastolic filling velocity (active filling from atrial contraction)
In healthy adults, the E wave is typically larger than the A wave (E/A > 1), reflecting normal LV relaxation and filling dynamics.
Clinical Significance of Reversed E/A Ratio
When E/A ≤ 0.8 with E velocity ≤50 cm/sec:
- Indicates Grade I diastolic dysfunction (impaired relaxation pattern)
- Left atrial pressure is normal or low
- Represents the earliest stage of diastolic dysfunction
- Most commonly seen in hypertensive heart disease, early cardiomyopathy, or aging 1
When E/A ≤ 0.8 with E velocity >50 cm/sec:
This requires additional parameters to determine if filling pressures are elevated:
- E/e' ratio (average >14 suggests elevated pressures)
- TR jet velocity (>2.8 m/sec suggests elevated pressures)
- LA volume index (>34 mL/m² suggests chronically elevated pressures)
- If ≥2 of these 3 parameters are abnormal, this indicates Grade II diastolic dysfunction with elevated left atrial pressure 1
Critical Pitfalls to Avoid
Age Considerations
In young individuals (<40 years), E/A ratios >2 may be physiologically normal, so other parameters must confirm normal diastolic function (particularly normal e' velocities) 1
Respiratory Variation
The E/A ratio can reverse with respiration - some patients show E/A <1 on inspiration but >1 on expiration, which may represent early diastolic dysfunction that is more sensitively detected at end-inspiration 2
Post-Cardioversion LA Stunning
After cardioversion, LA stunning causes markedly reduced A velocity, creating a falsely elevated E/A ratio that mimics restrictive physiology despite normal filling pressures. In this scenario, use deceleration time instead of E/A ratio for assessment 1
Valvular Disease Confounders
- Mitral regurgitation: Increases E velocity and decreases S/D ratio, mimicking elevated pressures
- Mitral stenosis: Transmitral velocities reflect valve disease, not LV function; use IVRT and other parameters instead 1
The Diastolic Dysfunction Progression
The E/A ratio follows a U-shaped curve as diastolic dysfunction worsens:
- Grade I (impaired relaxation): E/A <0.8 with low E velocity - normal filling pressures
- Grade II (pseudonormal): E/A 0.8-2 - elevated filling pressures (requires additional parameters to confirm)
- Grade III (restrictive): E/A ≥2 with short deceleration time (<160 msec) - markedly elevated filling pressures 1
The key clinical implication: A reversed E/A ratio alone does not indicate elevated filling pressures or heart failure - it represents early diastolic dysfunction with preserved filling pressures in most cases. However, it signals the beginning of a progressive disease process that requires monitoring and treatment of underlying conditions (hypertension, ischemia, etc.).