When should heart failure be diagnosed?

When to Diagnose Heart Failure

Heart failure should be diagnosed when a patient presents with typical symptoms (breathlessness, ankle swelling, fatigue) AND has objective evidence of cardiac dysfunction (structural or functional abnormality) at rest, with additional confirmation from natriuretic peptide testing in uncertain cases. 1

Diagnostic Criteria

The European Society of Cardiology (ESC) defines heart failure as a clinical syndrome characterized by:

1. Typical symptoms: Breathlessness, ankle swelling, fatigue
2. Possible signs: Elevated jugular venous pressure, pulmonary crackles, peripheral edema
3. Objective evidence of cardiac structural/functional abnormality causing reduced cardiac output and/or elevated intracardiac pressures

Required Components for Diagnosis

• Symptoms consistent with heart failure
• Objective evidence of cardiac dysfunction (preferably by echocardiography)
• In doubtful cases, a response to treatment directed at heart failure 1

Diagnostic Algorithm

For non-acute presentation:

1. Initial assessment: Evaluate probability of HF based on:

   • Prior clinical history (CAD, hypertension, diuretic use)
   • Presenting symptoms (orthopnea)
   • Physical examination (bilateral edema, JVP, displaced apex)
   • Resting ECG

2. Natriuretic peptide testing if at least one element is abnormal:

   • BNP < 35 pg/mL or NT-proBNP < 125 pg/mL makes HF unlikely
   • Higher values require further evaluation with echocardiography 1

3. Echocardiography to confirm diagnosis and classify type of heart failure:

   • HFrEF: LVEF < 40%
   • HFmrEF: LVEF 40-49%
   • HFpEF: LVEF ≥ 50% 1

Classification Based on Ejection Fraction

The 2016 ESC guidelines classify heart failure into three categories:

• HF with reduced EF (HFrEF): LVEF < 40%
• HF with mid-range EF (HFmrEF): LVEF 40-49%
• HF with preserved EF (HFpEF): LVEF ≥ 50% 1

Specific Criteria for HFpEF

For HFpEF diagnosis, all of the following must be present:

1. Symptoms and/or signs of heart failure
2. LVEF ≥ 50%
3. Elevated natriuretic peptides (BNP > 35 pg/mL and/or NT-proBNP > 125 pg/mL)
4. Objective evidence of other cardiac functional/structural alterations (LV hypertrophy, LA enlargement, diastolic dysfunction) 1

Diagnostic Pitfalls and Challenges

• Non-specific symptoms: Breathlessness, fatigue, and ankle swelling can have multiple causes
• Normal ECG: Makes HF diagnosis unlikely (negative predictive value >90%) 1
• Elderly patients: Symptoms may be attributed to aging or other conditions
• Obesity: Can mask or mimic HF symptoms
• Co-morbidities: Conditions like COPD can present with similar symptoms 1

Additional Diagnostic Tests

• 12-lead ECG: Should be performed in all patients with suspected HF 1
• Chest X-ray: Useful to detect cardiomegaly and pulmonary congestion 1
• Laboratory tests: Complete blood count, electrolytes, renal function, liver function, thyroid function, lipid profile, glucose 1
• Coronary angiography: For patients with angina or significant ischemia 1

Important Considerations

• Heart failure is a syndrome, not a final diagnosis - the underlying etiology must always be identified
• Asymptomatic cardiac dysfunction is a precursor to HF and should be recognized early
• The relationship between symptoms and severity of cardiac dysfunction is often poor
• Response to treatment alone is not sufficient for diagnosis but should generally show some improvement 1

By following this structured approach to diagnosis, clinicians can accurately identify heart failure and classify it appropriately to guide effective treatment strategies.