What is the difference between Heart Failure with preserved Ejection Fraction (HFpEF) and diastolic dysfunction?

Differentiating Heart Failure with Preserved Ejection Fraction (HFpEF) from Diastolic Dysfunction

Diastolic dysfunction is a precursor to HFpEF, while HFpEF is a clinical syndrome requiring both diastolic dysfunction and heart failure symptoms despite preserved ejection fraction (≥50%). 1

Key Differences

Definition and Diagnostic Criteria

• Diastolic dysfunction refers to impaired left ventricular relaxation and/or filling, which can be detected on echocardiography in asymptomatic individuals 1, 2
• HFpEF is a clinical syndrome characterized by:
  • Heart failure symptoms (dyspnea, fatigue, exercise intolerance)
  • LVEF ≥50% (preserved)
  • Evidence of diastolic dysfunction
  • Elevated natriuretic peptides 1

Clinical Presentation

• Diastolic dysfunction may be entirely asymptomatic and is often an incidental finding on echocardiography 1
• HFpEF presents with clinical symptoms of heart failure despite normal LVEF, including shortness of breath (especially on exertion), fatigue, and signs of congestion 1, 3
• In a study of elderly primary care patients with exertional dyspnea, 16% had unrecognized heart failure, with 12% having HFpEF 1

Pathophysiology

• Both conditions involve impaired LV relaxation, increased LV stiffness, and elevated filling pressures 1, 2
• HFpEF patients demonstrate significantly lower longitudinal and circumferential strains compared to both normal patients and those with asymptomatic diastolic dysfunction 1
• HFpEF patients have significantly more impaired right ventricular and left atrial function than matched asymptomatic patients with diastolic dysfunction 1

Diagnostic Approach

Echocardiographic Parameters

• Key parameters for assessing diastolic function include:
  • E/e' ratio (early mitral inflow velocity to early diastolic mitral annular velocity)
  • Left atrial volume index (LAVI)
  • Tricuspid regurgitation peak velocity 1
• E/e' >14 is generally indicative of diastolic dysfunction in most guidelines 1
• Several TTE parameters, including E/e', LAVI, and pulmonary vein flow patterns have the greatest value in diagnosing HFpEF (sensitivity 77%, specificity 81%) 1

Biomarkers

• Natriuretic peptides (BNP, NT-proBNP) are typically elevated in HFpEF but may be normal in isolated diastolic dysfunction 1
• For diagnosing HFpEF, the combination of NT-proBNP measurement and TTE with tissue Doppler imaging is superior to using either one alone 1
• Natriuretic peptide levels are generally lower in HFpEF compared to HFrEF and can be affected by comorbidities like obesity and atrial fibrillation 1

Advanced Imaging

• Speckle tracking echocardiography can detect subtle systolic dysfunction in HFpEF patients despite normal LVEF 1, 4
• Exercise echocardiography may help identify HFpEF in challenging cases, especially high-risk patients 1
• Cardiac MRI with late gadolinium enhancement can detect myocardial fibrosis, which is an independent predictor of outcomes in HFpEF 1

Clinical Implications

Prognosis

• Asymptomatic diastolic dysfunction can progress to HFpEF over time 5
• HFpEF has poor prognosis similar to heart failure with reduced ejection fraction (HFrEF) 3
• In HFpEF patients, global LV longitudinal strain measured using speckle tracking can help predict 30-day readmission 1
• Abnormal indices of left atrial mechanics, especially LA reservoir strain, are powerful prognostic factors in HFpEF 1

Treatment Challenges

• While treatments for HFrEF are well-established, no therapies have consistently shown mortality benefits specifically for HFpEF 1, 3
• Recent guidelines suggest SGLT2 inhibitors and diuretics for symptom management in HFpEF 1
• Treatments targeting the underlying mechanisms of diastolic dysfunction (such as addressing oxidative stress) are being investigated 2

Special Considerations

Diagnostic Challenges in Atrial Fibrillation

• Assessing diastolic function and diagnosing HFpEF in patients with atrial fibrillation is particularly challenging due to:
  • Variable cycle length
  • Absence of atrial contraction
  • Frequent left atrial enlargement regardless of LV filling pressures 6
• A two-step algorithm combining echocardiographic parameters with body mass index has been proposed to differentiate normal from elevated LV filling pressures in AF patients 6

Concealed Systolic Dysfunction

• Despite normal LVEF, up to 83% of HFpEF patients have some alteration in systolic function when assessed with more sensitive measures 4
• Stress-corrected midwall shortening (circumferential function) identifies more patients with concealed LV systolic dysfunction than longitudinal shortening measurements 4