How should heart failure be diagnosed in an ideal setting and in a low‑resource setting to allow initiation of treatment?

Diagnosing Heart Failure: Ideal and Low-Resource Settings

In ideal settings, diagnose heart failure through clinical assessment (history, physical exam, ECG) followed by natriuretic peptide testing (BNP >35 pg/mL or NT-proBNP >125 pg/mL) and echocardiography to confirm diagnosis and determine ejection fraction; in low-resource settings without access to natriuretic peptides or echocardiography, you can initiate treatment based on clinical criteria alone when history, symptoms, physical examination findings, and ECG abnormalities strongly suggest heart failure. 1

Ideal Setting Diagnostic Algorithm

Step 1: Clinical Assessment

Begin with these specific elements that have independent diagnostic value:

• History elements to assess: 1, 2

  • Age (older patients more likely)
  • Prior coronary artery disease (likelihood ratio 7.1)
  • History of myocardial infarction (greatly increases likelihood)
  • Hypertension
  • Current loop diuretic use
  • History of pulmonary edema (likelihood ratio 54.2)

• Key symptoms to identify: 1, 3, 4

  • Orthopnea (likelihood ratio 39.1)
  • Paroxysmal nocturnal dyspnoea (likelihood ratio 35.5)
  • Breathlessness when walking on flat surfaces (likelihood ratio 25.8)
  • Peripheral edema
  • Bendopnea

• Physical examination findings with high diagnostic value: 1, 2, 4

  • Displaced apical beat
  • Increased jugular venous pressure (>6 cm)
  • Third heart sound/ventricular gallop (likelihood ratio 30.0)
  • Heart murmur
  • Pulse irregularity
  • Rales on pulmonary auscultation (likelihood ratio 23.3)
  • Bilateral lower limb edema combined with hepatic enlargement and elevated JVP (likelihood ratio 130.3)
  • Heart rate >110 bpm (likelihood ratio 26.7)

Critical point: If history, physical examination, and resting ECG are ALL normal, heart failure is highly unlikely and other diagnoses should be considered. 1

Step 2: Natriuretic Peptide Testing

Use natriuretic peptides as a gatekeeper test when echocardiography is not immediately available: 1

• Cut-off values for ruling OUT heart failure (non-acute setting):

  • BNP <35 pg/mL
  • NT-proBNP <125 pg/mL
  • Negative predictive value: 0.94-0.98

• Important caveat: Natriuretic peptides are excellent for ruling OUT heart failure but should NOT be used alone to establish the diagnosis (positive predictive value only 0.44-0.57 in non-acute settings). 1

• If natriuretic peptides are elevated AND clinical assessment is abnormal, proceed to echocardiography. 1

Step 3: Echocardiography (Diagnostic Standard)

Echocardiography is the most useful, widely available test to establish the diagnosis and is crucial for determining appropriate treatment: 1

• Provides information on:

  • Left ventricular ejection fraction (LVEF)
  • Chamber volumes
  • Ventricular systolic and diastolic function
  • Wall thickness
  • Valve function
  • Pulmonary hypertension

• Classification based on LVEF: 1

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

Step 4: Additional Testing in Ideal Settings

Once heart failure is confirmed, obtain: 5

• Complete blood count
• Serum electrolytes, BUN, creatinine
• Liver function tests
• Blood glucose
• Lipid panel
• Thyroid-stimulating hormone
• Urinalysis
• Consider: serum ferritin, HIV test, ANA, rheumatoid factor in selected patients

Low-Resource Setting Diagnostic Approach

When natriuretic peptides and echocardiography are unavailable, you can diagnose and initiate treatment based on clinical criteria alone: 1, 2, 4

Clinical Diagnosis Without Advanced Testing

Sufficient to initiate treatment when you have:

1. Strong clinical history: 1, 2

   • Prior myocardial infarction or known coronary artery disease
   • Hypertension
   • Age >65 years
   • History of pulmonary edema

2. Multiple characteristic symptoms: 4

   • Orthopnea
   • Paroxysmal nocturnal dyspnoea
   • Dyspnea on exertion or at rest
   • Peripheral edema

3. Objective physical findings: 1, 2

   • Displaced apex beat
   • Elevated jugular venous pressure
   • Third heart sound
   • Bilateral rales
   • Peripheral edema
   • Tachycardia

4. ECG abnormalities (any abnormality increases likelihood): 1

   • Prior myocardial infarction
   • Left ventricular hypertrophy
   • Atrial fibrillation
   • Bundle branch block

5. Chest X-ray findings (if available): 6, 5

   • Venous congestion
   • Interstitial edema
   • Cardiomegaly
   • Pleural effusion

A simplified diagnostic rule combining 3 history items (age, coronary artery disease, loop diuretic use) plus 6 physical examination findings (pulse rate and regularity, displaced apex beat, rales, heart murmur, increased jugular venous pressure) showed excellent diagnostic accuracy (c-statistic 0.83). 2

Initiating Treatment in Low-Resource Settings

You can safely initiate treatment when clinical probability is high based on the above criteria: 1

• Start with loop diuretics for symptomatic relief of congestion 1
• Add ACE inhibitors (starting at low doses) 1
• Monitor clinical response through symptoms, signs, and daily weight 1

Important monitoring in low-resource settings: 1

• Check blood pressure, renal function, and electrolytes 1-2 weeks after starting ACE inhibitors
• Assess volume status through physical examination
• Daily self-weighing by patient
• Monitor for symptom improvement or worsening

Common Pitfalls to Avoid

In both settings:

• Don't rely on symptoms and signs alone without considering their likelihood ratios - many symptoms have low sensitivity (<36%) even when present in confirmed heart failure. 4

• Don't dismiss heart failure in patients with mild or atypical symptoms - 35.5% of patients with confirmed cardiac dysfunction are in NYHA class I. 4

• Don't use elevated natriuretic peptides alone to diagnose heart failure - positive predictive value is only 0.44-0.57; always confirm with echocardiography when available. 1

• Don't assume heart failure is absent just because classic signs are missing - signs like gallop rhythm, rales, and severe edema are infrequent even in confirmed heart failure (sensitivity <10%). 4

In low-resource settings specifically:

• Don't delay treatment waiting for advanced testing if clinical probability is high - the combination of history, physical examination, and ECG provides sufficient diagnostic accuracy to initiate therapy. 1, 2

• Don't use thiazide diuretics as monotherapy if you suspect reduced kidney function - loop diuretics are more effective in this setting. 1

• Don't start ACE inhibitors without a plan for monitoring renal function and electrolytes - check within 1-2 weeks of initiation. 1