What are the recommended outpatient tests to diagnose heart failure?

Recommended Outpatient Tests for Heart Failure Diagnosis

For outpatient evaluation of suspected heart failure, you should obtain: 12-lead ECG, natriuretic peptides (BNP or NT-proBNP), and transthoracic echocardiography with Doppler as your core diagnostic triad, supplemented by basic laboratory tests and chest X-ray. 1

Initial Diagnostic Approach

Essential First-Line Tests

12-Lead Electrocardiogram

• Obtain in all patients with suspected heart failure 1
• A normal ECG has >90% negative predictive value for excluding left ventricular systolic dysfunction 1, 2
• Provides critical information about heart rhythm, rate, QRS morphology and duration needed for treatment planning 1

Natriuretic Peptides (BNP or NT-proBNP)

• Measure when clinical diagnosis is uncertain in the outpatient setting 1, 2
• Use cut-off values: NT-proBNP <125 pg/mL or BNP <35 pg/mL makes heart failure unlikely in non-acute presentations 1
• Has the highest diagnostic contribution beyond history and physical examination (increases diagnostic accuracy from c-statistic 0.83 to 0.86) 3
• Particularly valuable as a "rule out" test due to consistently high negative predictive value 1, 2

Transthoracic Echocardiography with Doppler

• This is the definitive diagnostic test and method of choice 1, 2
• Required to provide objective evidence of cardiac dysfunction at rest, which is necessary for diagnosis 1, 2
• Measures left ventricular ejection fraction (LVEF) to distinguish HFrEF (LVEF <40-45%) from HFpEF (LVEF ≥50%) 1, 4
• Assesses ventricular size, wall thickness, wall motion, valve function, and diastolic parameters 1
• Use modified biplane Simpson's rule for LVEF measurement; avoid Teichholz/Quinones methods 1

Recommended Laboratory Tests

Standard Blood Work (obtain at initial evaluation) 1:

• Complete blood count (hemoglobin, hematocrit, white blood cells, platelets)
• Serum electrolytes: sodium, potassium, calcium, magnesium
• Renal function: blood urea nitrogen, creatinine with estimated GFR
• Liver function tests: bilirubin, AST, ALT, GGTP
• Fasting blood glucose and HbA1c
• Lipid profile
• Thyroid-stimulating hormone (TSH)
• Ferritin and transferrin saturation (TSAT/TIBC)
• Urinalysis

These tests identify reversible causes, assess suitability for specific therapies, and detect comorbidities that interfere with heart failure management 1.

Chest X-Ray

• Obtain initially to detect alternative pulmonary diseases contributing to dyspnea 1
• More useful in acute settings than non-acute outpatient presentations 1
• Can show pulmonary venous congestion or edema, though significant LV dysfunction may exist without cardiomegaly 1

Diagnostic Algorithm for Outpatient Setting

Step 1: If ECG is normal AND natriuretic peptides are below threshold (NT-proBNP <125 pg/mL or BNP <35 pg/mL), heart failure is unlikely 1

Step 2: If ECG is abnormal OR natriuretic peptides are elevated, proceed to echocardiography 1

Step 3: Echocardiography confirms diagnosis and classifies heart failure type based on LVEF 1, 2

Additional Tests in Selected Patients

Coronary Evaluation

• Coronary arteriography is recommended for patients with angina or significant ischemia 1
• Consider in patients with chest pain of uncertain cardiac origin or known/suspected coronary disease without angina 1

Specialized Testing (when clinically indicated) 1:

• Hemochromatosis screening
• Sleep-disordered breathing evaluation
• HIV testing
• Rheumatologic disease panels, amyloidosis testing, or pheochromocytoma workup when clinical suspicion exists

Exercise Testing

• Limited diagnostic value but useful to exclude heart failure if normal maximal test in untreated patient 1
• Consider cardiopulmonary exercise testing to identify cause of unexplained dyspnea 1

Common Pitfalls to Avoid

• Do not rely on chest X-ray alone; it has limited diagnostic value in non-acute outpatient settings 1
• Do not use Teichholz or Quinones methods for LVEF calculation—these are inaccurate 1
• Do not skip natriuretic peptide testing when diagnosis is uncertain; it provides the largest additional diagnostic contribution beyond clinical assessment 3
• Remember that nearly 40% of patients may not undergo echocardiography in real-world outpatient settings, but this is suboptimal care 5
• Be aware that natriuretic peptides can be elevated in elderly patients (>75 years), atrial arrhythmias, LV hypertrophy, COPD, and chronic kidney disease 1