Diastolic Dysfunction Grade I–III — ASE/EACVI Classification (Updated 2026)

Concise overview of echocardiographic assessment and grading of diastolic dysfunction using the updated ASE 2025 algorithm, including a pragmatic clinical alternative

Diastolic Function in 2025: A Practical Approach Based on the New ASE Recommendations

Introduction: Why Diastolic Function Matters

Heart failure with preserved ejection fraction (HFpEF) accounts for a large proportion of heart failure cases. The key abnormality is impaired LV relaxation and/or increased stiffness, which may lead to elevated filling pressures despite preserved LVEF.

Echocardiography remains the primary tool for assessing diastolic function. The updated ASE 2025 recommendationssimplify the initial assessment and aim to reduce indeterminate results.

A major change compared with the 2016 algorithm is that left atrial volume is no longer part of the primary assessment, reflecting its limited reliability as a marker of current filling pressure. Instead, the initial evaluation focuses on e′, E/e′, and TR velocity/PASP.

If these parameters are discordant or cannot be reliably obtained, additional markers such as LA reservoir strain, pulmonary venous flow, LAVi, and IVRT are used to clarify filling pressure and minimize intermediate or indeterminate classifications.

This article focuses on the Figure 3 algorithm for grading diastolic dysfunction and estimating left atrial pressure (LAP).

Core Principles – ASE 2025

No single parameter is diagnostic
Use a multiparametric, stepwise approach
The algorithm can be applied regardless of LVEF
Initial assessment focuses on:
- e′
- E/e′
- TR velocity / PASP

Step 1: Three Key Parameters

Assess together:

e′
- Abnormal if average e′ ≤ 6.5 cm/s
E/e′
- Abnormal if average E/e′ ≥ 14
TR velocity / PASP
- Abnormal if TR velocity ≥ 2.8 m/s
- or PASP ≥ 35 mmHg

Normal Diastolic Function

If all three are normal:

→ Normal diastolic function / normal LAP

Grade I – Impaired Relaxation

If only e′ is reduced:

E/e′ normal
TR velocity / PASP normal

Then assess E/A:

E/A ≤ 0.8 → Grade I
E/A > 0.8 → proceed to Step 2

Grade I is associated with normal resting LAP.

When to Proceed to Step 2

Step 2 is required if:

reduced e′ with E/A > 0.8
only E/e′ abnormal
only TR velocity / PASP abnormal
two of the three primary parameters abnormal

If all three are abnormal:

→ elevated LAP

Step 2: Assessment of Filling Pressure

Additional parameters:

LAVi > 34 mL/m²
LARS ≤ 18%
Pulmonary vein S/D ratio ≤ 0.67

Alternative:

IVRT ≤ 70 ms

Interpretation:

≥1 abnormal → elevated LAP
all normal → LAP likely normal

Pragmatic Clinical Alternative

In daily practice, pulmonary venous flow may be difficult to obtain and LA strain may not be available.

A simplified approach may therefore use:

LAVi > 34 mL/m² → supports elevated LAP
if LAVi is normal or inconclusive:
IVRT ≤ 70 ms → supports elevated LAP

This is a practical simplification, not a replacement for the full ASE algorithm.

Grade II and III

If elevated LAP is present:

E/A < 2.0 → Grade II
E/A ≥ 2.0 → Grade III

Summary

Grade	Main findings	LAP
Normal	All 3 primary parameters normal	Normal
Grade I	Reduced e′, E/A ≤0.8	Normal
Grade II	Elevated LAP, E/A <2	Elevated
Grade III	Elevated LAP, E/A ≥2	Markedly elevated

Important Updates vs. 2016

stronger emphasis on a multiparametric approach
initial assessment with e′, E/e′ and TR velocity/PASP
integration of LA strain
defined role of IVRT
clearer handling of intermediate cases

Limitations

The standard algorithm should not be applied without modification in:

atrial fibrillation
significant mitral valve disease
relevant mitral annular calcification
pulmonary hypertension of non-cardiac origin
LVAD / transplant
constrictive pericarditis

Conclusion

The ASE 2025 Figure 3 algorithm provides a practical approach:

Start with e′, E/e′ and TR velocity/PASP
Use Step 2 for intermediate patterns
Confirm elevated LAP before grading
E/A <2 → Grade II
E/A ≥2 → Grade III

A simplified LAVi + IVRT approach may be useful when more advanced measurements are unavailable.

References

Nagueh SF, Sanborn DY, Oh JK, et al. Recommendations for the Evaluation of Left Ventricular Diastolic Function by Echocardiography and for Heart Failure With Preserved Ejection Fraction Diagnosis: An Update From the American Society of Echocardiography. J Am Soc Echocardiogr. 2025.
Nagueh SF, Smiseth OA, Appleton CP, et al. Recommendations for the Evaluation of Left Ventricular Diastolic Function by Echocardiography. J Am Soc Echocardiogr. 2016;29:277–314.