What are the echocardiographic criteria (including transmitral E/A ratio, deceleration time, early diastolic mitral annular velocity, E/e′ ratio, and left atrial volume index) that define grade 1 diastolic dysfunction (impaired relaxation)?

Grade 1 Diastolic Dysfunction Parameters

Grade 1 diastolic dysfunction is defined by impaired relaxation with normal or low left atrial pressure, characterized by E/A ratio ≤0.8 with peak E velocity ≤50 cm/s, average E/e′ <14, left atrial volume index <34 mL/m², and tricuspid regurgitation jet velocity <2.8 m/s. 1, 2

Core Echocardiographic Criteria

Transmitral Flow Pattern (Pulsed-Wave Doppler)

• E/A ratio ≤0.8 is the primary defining characteristic, reflecting impaired early diastolic filling relative to atrial contribution 3, 1, 2
• Peak E velocity ≤50 cm/s specifically identifies normal or low mean left atrial pressure and confirms Grade 1 classification 1, 2
• Deceleration time (DT) is typically prolonged (>200 ms), reflecting slow left ventricular pressure decline during early diastolic filling 3, 1
• When peak E velocity is >50 cm/s despite E/A ≤0.8, additional parameters must be assessed to exclude pseudonormalization 1, 2

Tissue Doppler Imaging of Mitral Annulus

• Septal e′ velocity may be reduced (<7 cm/s) but is not required for Grade 1 diagnosis 3, 1
• Lateral e′ velocity may be reduced (<10 cm/s) but is not required for Grade 1 diagnosis 3, 1
• Average E/e′ ratio <14 (typically <8 in Grade 1) confirms normal filling pressures and distinguishes Grade 1 from higher grades 1, 2
• The reduced e′ velocities reflect impaired myocardial relaxation, the fundamental abnormality in Grade 1 dysfunction 1

Left Atrial Assessment

• Left atrial volume index <34 mL/m² is essential for Grade 1 diagnosis, as enlargement indicates chronically elevated pressures consistent with at least Grade 2 dysfunction 1, 2
• Normal left atrial size confirms that filling pressures have not been chronically elevated 1

Pulmonary Pressures

• Tricuspid regurgitation jet velocity <2.8 m/s indicates normal pulmonary artery systolic pressure and excludes elevated left-sided pressures 1, 2

Algorithmic Approach to Classification

Primary Assessment

• Measure transmitral E and A velocities and calculate E/A ratio 1
• If E/A ≤0.8 AND peak E ≤50 cm/s, Grade 1 diastolic dysfunction is present with normal left atrial pressure 1, 2

When E Velocity is Elevated (>50 cm/s)

• Assess three supplemental parameters: average E/e′, left atrial volume index, and tricuspid regurgitation velocity 1
• If <50% of available parameters are abnormal (i.e., 0 or 1 out of 3), left atrial pressure remains normal and Grade 1 is confirmed 1, 2
• If ≥50% are abnormal, the pattern represents Grade 2 (pseudonormal) dysfunction despite E/A ≤0.8 1

Hemodynamic Interpretation

• Grade 1 represents impaired relaxation with normal or low filling pressures, distinguishing it from all higher grades 3, 2
• The pathophysiology centers on delayed myocardial relaxation without chamber remodeling or pressure elevation 1
• Isovolumetric relaxation time (IVRT) is typically prolonged (>110 ms in some references), reflecting slow left ventricular pressure decline 4, 5

Pulmonary Venous Flow (Supplementary)

• Systolic-to-diastolic (S/D) ratio >1 is consistent with normal left atrial pressure in Grade 1 dysfunction 4, 5
• Pulmonary venous atrial reversal (AR) velocity is typically normal (<0.25 m/s) 4
• These parameters provide confirmatory evidence when transmitral flow is equivocal 1

Common Pitfalls and Caveats

• Age-related changes: E/A ratio naturally decreases with age; an E/A <1 may be normal in elderly patients and should be interpreted with clinical context 6
• Pseudonormalization: An apparently normal E/A ratio (0.8–2.0) may mask underlying dysfunction; assess supplemental parameters (E/e′, left atrial volume index, tricuspid regurgitation velocity) to unmask Grade 2 dysfunction 3, 1
• Valsalva maneuver can unmask pseudonormalization by reducing preload; a decrease in E/A during strain confirms elevated baseline pressures inconsistent with Grade 1 3, 1
• Loading conditions: Acute volume depletion or diuresis may artificially lower E velocity and mimic Grade 1 pattern 6

Limitations of Assessment

• The algorithm does not apply in atrial fibrillation, significant mitral valve disease (stenosis, ≥moderate regurgitation, moderate annular calcification), left bundle branch block, paced rhythms, or ventricular assist device support 1, 4
• In atrial fibrillation, A-wave is absent; use deceleration time, IVRT, E/e′ ratio, and pulmonary venous S-wave instead 4
• Sinus tachycardia may cause E and A wave fusion, limiting interpretation; heart rate should be considered when measuring deceleration time 3

Clinical Significance

• Grade 1 dysfunction represents early disease that typically progresses to Grade 2 as severity advances 3
• Normal chamber dimensions with impaired relaxation are characteristic; left ventricular or atrial dilatation suggests alternative diagnoses or progression beyond Grade 1 1
• The presence of Grade 1 dysfunction warrants addressing primary etiologies such as hypertension, coronary artery disease, and diabetes to prevent progression 2