How do you differentiate between systolic and diastolic heart failure?

Differentiating Systolic from Diastolic Heart Failure

The primary distinction between systolic and diastolic heart failure is based on left ventricular ejection fraction (LVEF), with systolic heart failure characterized by reduced LVEF (<40%) and diastolic heart failure characterized by preserved LVEF (≥40-50%) with evidence of abnormal diastolic function. 1

Key Diagnostic Parameters

Echocardiography - Primary Diagnostic Tool

• Left Ventricular Ejection Fraction (LVEF):
  • Systolic HF: LVEF <40% 1
  • Diastolic HF: LVEF ≥40-50% (preserved) 1, 2
• Chamber Size:
  • Systolic HF: Dilated left ventricle with increased end-diastolic volume 3
  • Diastolic HF: Normal or only slightly enlarged ventricle 4
• Diastolic Function Assessment:
  • Mitral inflow patterns (E/A ratio):
    • Grade I (mild): Impaired relaxation pattern (E/A ratio ≤0.8) 2
    • Grade II (moderate): Pseudonormal pattern (E/A ratio >0.8 but <2) 2
    • Grade III (severe): Restrictive pattern (E/A ratio ≥2) 2
  • Tissue Doppler Imaging (TDI): Reduced peak E' velocity in diastolic dysfunction 1

Clinical Presentation

Both types present with similar symptoms and signs, making clinical differentiation difficult 5, 6:

• Dyspnea
• Fatigue
• Signs of fluid retention (peripheral edema, pulmonary rales)
• Jugular venous distention

Laboratory Testing

• BNP/NT-proBNP: Elevated in both types, cannot reliably distinguish between systolic and diastolic dysfunction 1
• Other lab tests: Complete blood count, electrolytes, renal function, liver function, and thyroid function to identify potential causes or comorbidities 1

Radiographic Findings

• Chest X-ray:
  • Systolic HF: Often shows cardiomegaly 4
  • Diastolic HF: May show pulmonary congestion with normal or only slightly enlarged cardiac silhouette 4

Diagnostic Algorithm

1. Initial Assessment:

   • Evaluate symptoms and signs of heart failure
   • Perform ECG (abnormal in most heart failure cases but not specific for type) 1
   • Order chest X-ray to assess for cardiomegaly and pulmonary congestion 1
   • Measure BNP/NT-proBNP levels (elevated in heart failure but doesn't differentiate type) 1

2. Definitive Diagnosis:

   • Perform echocardiography with Doppler studies (most important diagnostic test) 1
     • Measure LVEF
     • Assess chamber size and wall thickness
     • Evaluate diastolic function parameters (E/A ratio, deceleration time, E/e' ratio)
     • Assess for structural abnormalities (valvular disease, hypertrophy)

3. Classification:

   • If LVEF <40% → Systolic heart failure (HF with reduced EF) 1
   • If LVEF ≥40-50% with evidence of diastolic dysfunction → Diastolic heart failure (HF with preserved EF) 1, 2

Important Considerations

• Coexistence: Most patients with heart failure have elements of both systolic and diastolic dysfunction 1, 3
• Prognostic Implications: Mortality rates for diastolic heart failure are similar to those for systolic heart failure 3, 6
• Treatment Differences: Treatment approaches differ between the two types:
  • Systolic HF: ACE inhibitors, beta-blockers, diuretics, aldosterone antagonists 4
  • Diastolic HF: Blood pressure control, rate control, diuretics for congestion 2, 4

Common Pitfalls to Avoid

• Overlooking diastolic dysfunction when LVEF is normal in a patient with heart failure symptoms 6
• Missing pseudonormalized filling pattern (Grade II diastolic dysfunction) which can appear normal on standard echocardiography without tissue Doppler imaging 6
• Relying solely on clinical presentation to differentiate between systolic and diastolic heart failure 5, 6
• Assuming normal BNP excludes heart failure - while less likely, heart failure can still be present with normal BNP levels 7

By systematically evaluating LVEF and diastolic function parameters through echocardiography, clinicians can accurately differentiate between systolic and diastolic heart failure, which is crucial for appropriate management and improving patient outcomes.