What are the types of diastolic dysfunction?

Types of Diastolic Dysfunction

Diastolic dysfunction is classified into three distinct grades based on mitral inflow patterns, with each grade representing progressively worsening abnormalities in left ventricular filling and increasing left atrial pressures. 1

Classification System

Diastolic dysfunction is categorized into three grades according to the American Society of Echocardiography and the European Association of Cardiovascular Imaging 2:

Grade I (Mild): Impaired Relaxation Pattern

• E/A ratio ≤ 0.8 with peak E velocity ≤ 50 cm/sec
• Normal or low left atrial pressure
• Prolonged deceleration time
• Characterized by delayed early filling and increased dependence on atrial contraction
• Represents the earliest stage of diastolic dysfunction

Grade II (Moderate): Pseudonormal Pattern

• E/A ratio > 0.8 but < 2
• Elevated left atrial pressure
• Normal-appearing mitral inflow pattern that masks underlying dysfunction
• Can be unmasked with Valsalva maneuver (E/A ratio decreases to < 1)
• Requires additional parameters to confirm elevated left atrial pressure:
  • Average E/e' ratio > 14
  • Left atrial volume index > 34 mL/m²
  • Peak TR velocity > 2.8 m/sec

Grade III (Severe): Restrictive Filling Pattern

• E/A ratio ≥ 2
• Markedly elevated left atrial pressure
• Short deceleration time (< 150-160 msec)
• Short isovolumic relaxation time (< 50 msec)
• Decreased septal and lateral e' velocities (3-4 cm/sec)
• Associated with poor outcomes, especially in restrictive cardiomyopathy

Diagnostic Approach

The evaluation of diastolic function should include 2, 1:

1. Mitral inflow assessment: E/A ratio and deceleration time
2. Tissue Doppler imaging: Mitral annular e' velocity (septal and lateral)
3. Left atrial volume index: Marker of chronicity of elevated filling pressures
4. Tricuspid regurgitation velocity: Estimate of pulmonary artery systolic pressure
5. Pulmonary vein flow: S/D ratio and atrial reversal velocity

Clinical Significance

Each grade of diastolic dysfunction carries different prognostic implications 2, 1:

• Grade I: Generally better prognosis but indicates early cardiac dysfunction
• Grade II: Associated with increased risk of hospitalization for heart failure
• Grade III: Carries the worst prognosis with significantly lower 5-year survival rate (39% compared to 79% for Grade I and 95% for normal function)

Special Considerations

In specific cardiac conditions, diastolic dysfunction may present with characteristic patterns 2:

• Restrictive cardiomyopathy: Often presents with Grade III diastolic dysfunction
• Hypertrophic cardiomyopathy: May show any grade depending on disease severity
• Constrictive pericarditis: Can be distinguished by "annulus reversus" (septal e' higher than lateral e')

Pitfalls to Avoid

1. Mistaking pseudonormal pattern (Grade II) for normal diastolic function
2. Not using multiple parameters to confirm the grade of dysfunction
3. Failing to recognize the prognostic significance of diastolic dysfunction grades
4. Not accounting for age-related changes in diastolic parameters
5. Overlooking diastolic dysfunction in patients with preserved ejection fraction

The accurate assessment of diastolic function grade is essential for proper management and risk stratification of patients with heart failure, particularly those with preserved ejection fraction 2, 1.