What early mitral inflow velocity to early diastolic mitral annular velocity (E/e′) ratio threshold indicates diastolic dysfunction beyond grade 1, and which additional echocardiographic markers are needed to confirm elevated left‑ventricular filling pressures?

E/e' Ratio Threshold for Diastolic Dysfunction Beyond Grade 1

An average E/e' ratio >14 indicates that diastolic dysfunction has progressed beyond grade 1, signaling elevated left ventricular filling pressures consistent with grade II or higher diastolic dysfunction. 1

Understanding the E/e' Threshold

The E/e' ratio alone provides critical information but requires integration with other parameters for accurate grading:

• E/e' >14 is the established cutoff that indicates elevated left atrial pressure and confirms progression beyond grade 1 diastolic dysfunction 1
• Grade 1 diastolic dysfunction is characterized by impaired relaxation with normal or low filling pressures, fundamentally different from grades II-III which have elevated pressures 1
• When E/e' falls in the intermediate range (8-14), additional parameters become essential as diagnostic accuracy decreases substantially in this "gray zone" 2, 3

Additional Parameters Required When E/e' is Indeterminate

When the E/e' ratio is between 8-14 or unavailable, the following three parameters must be assessed to determine if filling pressures are elevated 1:

Primary Confirmatory Parameters:

1. Tricuspid regurgitation peak velocity >2.8 m/sec

   • Directly supports elevated LV filling pressures 1
   • Provides estimate of pulmonary artery systolic pressure when combined with right atrial pressure 1

2. Left atrial volume index >34 mL/m²

   • Reflects chronic elevation of filling pressures 1
   • LA enlargement indicates sustained pressure overload 1

3. Mitral annular e' velocities

   • Septal e' <7 cm/sec or lateral e' <10 cm/sec indicates impaired relaxation 1
   • These thresholds help identify underlying diastolic dysfunction 1

Algorithmic Approach for Grading:

If 2 out of 3 (or all 3) of the above parameters meet cutoff values → elevated LAP is present and grade II diastolic dysfunction is confirmed 1

If only 1 out of 3 parameters meets cutoff values → LAP is normal and grade I diastolic dysfunction remains the diagnosis 1

If only one parameter is available or there is discrepancy between two parameters → LAP and grade should not be reported 1

Mitral Inflow Pattern Context

The mitral E/A ratio provides essential context for interpretation 1, 4:

• E/A ≤0.8 with peak E velocity ≤50 cm/sec → Grade I (impaired relaxation, normal pressures) 1, 4
• E/A ≥2 → Grade III (restrictive filling, markedly elevated pressures) 1, 4
• E/A between 0.8-2 → Requires the additional parameters listed above for accurate grading 1

Secondary Parameters When Primary Criteria Unavailable

If one of the three main criteria cannot be obtained, pulmonary venous flow can provide supportive evidence 1:

• Pulmonary vein S/D ratio <1 (systolic-to-diastolic velocity ratio or time-velocity integral ratio) supports elevated filling pressures 1
• This parameter is particularly useful when TR velocity is not measurable 1

Emerging Parameter: Left Atrial Strain

Recent evidence suggests left atrial strain may enhance diagnostic accuracy in the E/e' gray zone 2:

• Peak atrial longitudinal strain (PALS) is independently associated with elevated intracardiac pressures even after adjusting for E/e' and other parameters 2
• PALS predicts NYHA class better than traditional ASE/EACVI diastolic dysfunction grading in patients with E/e' 8-14 2
• E/LASr ratio (E-to-left atrial reservoir strain) >2.7-3.2 shows excellent diagnostic performance (AUC 0.90) for elevated filling pressures 5

Critical Pitfalls to Avoid

Age considerations: In young individuals (<40 years), E/A ratios >2 may be physiologically normal, requiring verification with normal e' velocities to confirm normal diastolic function 1

Post-cardioversion: Use deceleration time instead of E/A ratio due to left atrial stunning causing falsely elevated E/A ratios despite normal filling pressures 1

Atrial fibrillation: E/A ratio cannot be used; alternative parameters include E wave acceleration rate ≥1,900 cm/sec², IVRT ≤65 msec, and septal E/e' ≥11 4

Constrictive pericarditis: E/e' ratio should not be used to estimate filling pressures in this condition due to annulus reversus (septal e' > lateral e') 1

Never interpret E/e' in isolation: The ratio must always be integrated with clinical context, structural findings (LV hypertrophy, LA enlargement), and the complete echocardiographic assessment 1, 4