What is the diagnostic approach for heart failure?

Diagnosing Heart Failure

Heart failure diagnosis requires three essential components: clinical symptoms/signs, objective evidence of cardiac dysfunction on echocardiography (the gold standard), and an abnormal ECG or chest X-ray—a completely normal ECG makes heart failure highly unlikely. 1

Initial Clinical Assessment

Key Symptoms and Signs to Identify

• Dyspnea (exertional breathlessness or at rest), fatigue, and peripheral edema are the cardinal symptoms, though they lack specificity 1
• Displaced cardiac apex and third heart sound (S3) on physical examination are particularly useful findings 2
• Pulmonary rales indicating congestion 2
• A normal physical examination does NOT exclude heart failure, as there is poor correlation between symptoms and severity of cardiac dysfunction 1

Critical Initial Tests (Mandatory)

• 12-lead ECG: A normal ECG has >90% negative predictive value for excluding left ventricular systolic dysfunction—if the ECG is completely normal, reconsider the diagnosis 1
• Chest X-ray: Look for cardiomegaly and pulmonary congestion, though it has predictive value only when combined with typical symptoms and abnormal ECG 1
• Natriuretic peptides (BNP or NT-proBNP): Most useful as a "rule-out" test due to high negative predictive value; normal levels make heart failure unlikely in untreated patients 1

Important caveat: BNP can be falsely low in obesity, chronic stable heart failure on treatment, HFpEF, and African American patients—do not over-rely on BNP alone 3, 4

Definitive Diagnostic Testing

Echocardiography (The Diagnostic Standard)

Comprehensive 2D echocardiography with Doppler is the single most useful test and is mandatory to confirm heart failure. 1 It must answer three fundamental questions:

1. Is left ventricular ejection fraction (LVEF) preserved (≥50%) or reduced (≤40%)? This determines HFpEF vs HFrEF classification 1, 5
2. Is LV structure normal or abnormal? Measure ventricular dimensions/volumes, wall thickness, chamber geometry, and assess regional wall motion 1
3. Are there other structural abnormalities? Evaluate all valves for primary disease and secondary insufficiency (especially mitral/tricuspid regurgitation), assess right ventricular size and function, measure atrial dimensions 1

Additional hemodynamic data from echocardiography: Assess mitral inflow pattern, pulmonary venous inflow, mitral annular velocity (for LV filling characteristics), and tricuspid regurgitant gradient with IVC assessment (for pulmonary artery pressure estimation) 1

Essential Laboratory Workup

All patients with suspected heart failure require: 1

• Complete blood count (hemoglobin, WBC, platelets)
• Serum electrolytes (sodium, potassium)
• Renal function (creatinine with estimated GFR, urea)
• Liver function tests (bilirubin, AST, ALT, GGTP)
• Glucose and HbA1c
• Thyroid-stimulating hormone (TSH)
• Ferritin and transferrin saturation (TSAT/TIBC)
• Urinalysis
• Lipid panel 6

In acute exacerbations: Check cardiac-specific enzymes to exclude acute myocardial infarction 1

Additional Testing When Indicated

When Echocardiography is Insufficient

• Cardiac magnetic resonance (CMR): For tissue characterization, detecting infiltrative disease, or when echocardiography is technically limited 1
• Stress echocardiography or nuclear imaging: To detect reversible myocardial ischemia in patients with coronary artery disease 1
• Radionuclide angiography or contrast cineangiography: When clinical suspicion is high but echocardiogram is equivocal 6

Invasive Testing

• Coronary angiography: Recommended for patients with angina, intermediate-to-high CAD probability with ischemia on stress testing, or acute/severely decompensated heart failure not responding to initial treatment 1
• Hemodynamic monitoring (pulmonary artery catheterization): Consider in refractory cases, persistent hypotension, or uncertain LV filling pressures—NOT for routine use 1, 7
• Endomyocardial biopsy: Only to elucidate specific etiologies in selected cases 1

Exercise Testing

• Limited value for diagnosis but useful for: 1
  • Prognostic stratification (cardiopulmonary exercise testing with peak VO2)
  • Evaluation for heart transplantation
  • Identifying cause of unexplained dyspnea
• A normal maximal exercise test in an untreated patient excludes heart failure 1

Diagnostic Algorithm Summary

1. Clinical suspicion based on symptoms (dyspnea, fatigue, edema) and risk factors (CAD, hypertension, diabetes) 6, 2
2. Obtain ECG immediately—if completely normal, heart failure is unlikely 1
3. Check BNP/NT-proBNP—if normal in untreated patient, heart failure is unlikely (but beware false negatives) 1, 3
4. Chest X-ray—look for cardiomegaly and congestion 1
5. Echocardiography to confirm diagnosis—mandatory for all patients with suspected heart failure 1
6. Complete laboratory workup to identify etiology and comorbidities 1
7. Additional imaging or invasive testing only when diagnosis remains uncertain or to guide specific interventions 1

Common Diagnostic Pitfalls

• Over-reliance on BNP in obesity or HFpEF—levels may be falsely normal despite true heart failure 3, 4
• Accepting heart failure as a final diagnosis—always identify the underlying etiology (ischemic, valvular, hypertensive, etc.) 1
• Skipping echocardiography—clinical assessment alone is insufficient; objective evidence of cardiac dysfunction is mandatory 1
• Ignoring a normal ECG—this finding has excellent negative predictive value and should prompt reconsideration of the diagnosis 1
• Routine use of invasive hemodynamic monitoring—reserve for specific clinical scenarios, not standard practice 1, 7