Heart Failure Diagnostics
The diagnosis of heart failure requires three mandatory components: typical symptoms (dyspnea, fatigue, or ankle swelling), objective evidence of cardiac structural or functional abnormality at rest (preferably by echocardiography), and corroboration by elevated natriuretic peptides or signs of congestion—clinical suspicion alone is insufficient and must be confirmed by objective testing. 1
Initial Diagnostic Approach
Clinical Assessment
The diagnostic process begins with identifying typical symptoms, though these are non-specific and insufficient alone for diagnosis 2:
- Typical symptoms: Breathlessness (at rest or exertion), fatigue, tiredness, ankle swelling 2, 1
- More specific symptoms: Orthopnea, paroxysmal nocturnal dyspnea (less common in early disease) 2
- Physical signs: Elevated jugular venous pressure, pulmonary crackles, peripheral edema, displaced apical impulse, tachycardia, pleural effusion, hepatomegaly 2, 1
Critical pitfall: Symptoms and signs are particularly difficult to interpret in obese individuals, elderly patients, and those with chronic lung disease—objective testing is mandatory in these populations 2, 1. Many patients with suspected heart failure actually have alternative explanations including obesity, lung disease, or myocardial ischemia rather than true heart failure 3.
Risk Factor Assessment
Document the presence of conditions that substantially increase heart failure likelihood 4:
- Coronary artery disease (most common cause, accounting for 60-67% of cases) 2, 1
- Hypertension (present in 71% of heart failure patients, accounts for 17-31% of cases) 2, 1
- Diabetes mellitus (present in 35-43% of cases) 2, 4
- Previous myocardial infarction (43% of heart failure patients) 2
Mandatory Objective Testing
Electrocardiogram (First-Line)
An ECG must be obtained in all patients with suspected heart failure 2:
- A completely normal ECG has >90% negative predictive value for excluding left ventricular systolic dysfunction—if the ECG is entirely normal, the diagnosis of heart failure should be carefully reconsidered 2
- An abnormal ECG has poor positive predictive value but supports further evaluation 2
- QRS width >120 ms suggests cardiac dyssynchrony 2
Natriuretic Peptides (BNP/NT-proBNP)
Natriuretic peptide measurement provides the most powerful supplementary diagnostic contribution 5:
- Low-normal concentrations in untreated patients make heart failure unlikely and serve as an excellent "rule-out" test with very high negative predictive value 2, 1
- Elevated levels corroborate the diagnosis and have considerable prognostic value 2
- NT-proBNP measurement increases diagnostic accuracy (c-statistic from 0.83 to 0.86) with 69% net reclassification improvement 5
Echocardiography (Definitive Test)
Echocardiography is the preferred and necessary method for confirming heart failure 2:
- Objective evidence of cardiac dysfunction at rest is mandatory for diagnosis 2
- Left ventricular ejection fraction (LVEF) is the most important parameter for distinguishing systolic dysfunction (HF-REF) from preserved systolic function (HF-PEF) 2
- Provides assessment of valvular function, cardiac filling characteristics via Doppler, and helps determine etiology 2
Additional Initial Testing
Routine laboratory evaluation must include 2:
- Complete blood count (hemoglobin, leukocytes, platelets) 2
- Serum electrolytes, creatinine, glucose 2
- Hepatic enzymes and urinalysis 2
- Thyroid function (based on clinical findings) 2
- In acute exacerbations: cardiac enzymes to exclude myocardial infarction 2
Chest X-Ray
Chest radiography should be part of initial work-up 2:
- Useful for detecting cardiomegaly and pulmonary congestion 2
- Has predictive value only in context of typical symptoms and abnormal ECG 2
- Heart failure is highly unlikely with normal chest X-ray and absence of dyspnea 4
Determining Etiology
Heart failure should never be the final diagnosis—the underlying cause must be identified 2, 1:
- Coronary artery disease evaluation is warranted in all patients, especially with angina, as it is the most common cause 2, 6
- Consider stress echocardiography, nuclear cardiology, or cardiac MRI in patients with coronary disease 2
- Low voltage ECG with concentric thickening suggests infiltrative cardiomyopathy—cardiac MRI with late gadolinium enhancement is the definitive test 7
Advanced Testing (Selected Cases)
When Echocardiography is Insufficient
Additional non-invasive imaging should be considered 2:
- Stress echocardiography 2
- Nuclear cardiology 2
- Cardiac magnetic resonance imaging (CMR) for tissue characterization 2, 7
Tests of Limited Diagnostic Value
- Pulmonary function tests: Not valuable for diagnosing heart failure but useful for excluding respiratory causes of breathlessness 2
- Exercise testing: Limited diagnostic value; however, normal maximal exercise in untreated patients excludes heart failure 2
- Holter monitoring: No value for diagnosis; restrict to patients with symptomatic arrhythmias 2
Classification After Diagnosis
Once heart failure is confirmed, classify by 2, 1:
- Ejection fraction: HF-REF (reduced EF), HF-mEF (mid-range EF), HF-PEF (preserved EF) 1
- NYHA functional class (I-IV based on symptom severity and physical activity limitation) 2
- Stage: A (at risk), B (pre-heart failure), C (symptomatic), D (advanced/refractory) 1
Treatment Initiation
For patients with reduced LVEF and symptomatic heart failure 2:
- ACE inhibitors are recommended as first-line therapy 2
- Diuretics are essential when fluid overload is present (pulmonary congestion or peripheral edema), always combined with ACE inhibitors if possible 2
- Beta-blockers should be used in maximally tolerated doses 2
- Consider sacubitril/valsartan in patients with NYHA class II-IV and LVEF ≤40% who tolerate ACE inhibitors—this combination demonstrated superiority over enalapril alone in reducing cardiovascular death and heart failure hospitalization (HR 0.80, p<0.0001) 8