What are the criteria for diagnosing heart failure?

Diagnostic Criteria for Heart Failure

The diagnosis of heart failure requires both typical symptoms (dyspnea, fatigue, peripheral edema) AND objective evidence of cardiac dysfunction, usually through echocardiography, which is the preferred diagnostic method. 1

Clinical Assessment

• Typical symptoms include fatigue, dyspnea, and peripheral edema, though these are not specific to heart failure 1
• Initial examination should include assessment of volume status, orthostatic blood pressure changes, weight, height, and body mass index calculation 1
• A careful history should include current and past use of alcohol, illicit drugs, alternative therapies, and chemotherapy drugs 1
• There is often poor correlation between symptoms and the severity of cardiac dysfunction 1

Essential Diagnostic Tests

• Echocardiography with Doppler: The cornerstone of diagnosis that provides objective evidence of cardiac dysfunction at rest, which is necessary for the diagnosis 1

  • Measures left ventricular ejection fraction (LVEF) to distinguish between systolic dysfunction and preserved systolic function
  • Assesses valvular function, cardiac filling characteristics, and helps determine etiology 1

• 12-lead ECG: Should be performed in all patients with suspected heart failure 1

  • A normal ECG makes heart failure diagnosis unlikely (negative predictive value >90%) 1

• Chest X-ray: Part of initial workup to detect cardiomegaly and pulmonary congestion 1

  • Most valuable when interpreted alongside clinical signs/symptoms and ECG findings 1

• Laboratory tests: Initial evaluation should include 1:

  • Complete blood count
  • Urinalysis
  • Serum electrolytes (including calcium and magnesium)
  • Blood urea nitrogen and creatinine
  • Fasting blood glucose (glycohemoglobin)
  • Lipid profile
  • Liver function tests
  • Thyroid-stimulating hormone

• Natriuretic peptides (BNP and NT-proBNP): Useful when clinical diagnosis is uncertain 1

  • High negative predictive value makes them valuable as a "rule out" test 1
  • Helpful for risk stratification 1

Classification of Heart Failure

• Based on LVEF measurements, heart failure can be classified as 1:

  • Heart failure with reduced ejection fraction (HFrEF): LVEF <45-50%
  • Heart failure with preserved ejection fraction (HFpEF): LVEF ≥45-50% with evidence of diastolic dysfunction

• Diastolic dysfunction can be assessed through 1:

  • E/A ratio (mitral inflow pattern)
  • E/Ea ratio (tissue Doppler)
  • Deceleration time
  • Pulmonary vein flow

Additional Tests in Selected Cases

• Exercise testing: Limited value for diagnosis but useful for 1:

  • Excluding heart failure (a normal maximal exercise test rules out heart failure)
  • Prognostic stratification
  • Determining if heart failure is the cause of exercise limitation 1

• Coronary arteriography: Recommended for 1:

  • Patients with angina or significant ischemia
  • Patients with chest pain of uncertain origin who have no contraindications to revascularization
  • Patients with known/suspected coronary artery disease without angina 1

• Specialized tests when clinically indicated 1:

  • Screening for hemochromatosis, sleep-disturbed breathing, or HIV
  • Tests for rheumatologic diseases, amyloidosis, or pheochromocytoma
  • Endomyocardial biopsy when a specific diagnosis is suspected that would influence therapy

Common Pitfalls to Avoid

• Heart failure should never be the final diagnosis - always identify the underlying etiology 1
• Relying solely on symptoms for diagnosis is inadequate; objective evidence of cardiac dysfunction is essential 1
• A normal ECG makes heart failure unlikely - reconsider the diagnosis 1
• Endomyocardial biopsy should not be performed routinely, only when a specific diagnosis is suspected that would influence therapy 1
• Pulmonary function tests have limited value in diagnosing heart failure but are useful for excluding respiratory causes of breathlessness 1

Diagnostic Algorithm

1. Evaluate symptoms and signs (dyspnea, fatigue, peripheral edema)
2. Perform initial tests (ECG, chest X-ray, basic laboratory tests)
3. If clinical suspicion remains, measure natriuretic peptides
4. Confirm with echocardiography to assess cardiac structure and function
5. Determine if systolic or diastolic dysfunction (or both)
6. Identify underlying etiology through additional testing as needed
7. Classify severity using NYHA functional classification 1