In a patient with heart failure with preserved ejection fraction (HFpEF), what is the purpose of obtaining a standard posterior‑anterior and lateral chest X‑ray and how do its findings influence diagnosis and management?

Chest X-Ray in HFpEF: Essential Diagnostic Tool

Chest X-ray is a mandatory component of the diagnostic workup in HFpEF, serving to confirm pulmonary congestion, exclude alternative causes of dyspnea, and detect cardiomegaly, though findings are often less pronounced than in HFrEF. 1

Primary Diagnostic Purposes

1. Confirming Pulmonary Congestion

The chest X-ray provides objective evidence of cardiogenic pulmonary congestion, which is one of two key criteria in the Universal Definition of HF (the other being elevated natriuretic peptides). 2 Specific findings include:

• Pulmonary venous congestion - confirms elevated LV filling pressures and left heart failure 1
• Interstitial edema - indicates elevated LV filling pressures 1
• Pleural effusions - suggests elevated filling pressures, particularly if bilateral 1
• Kerley B lines - indicates increased lymphatic pressures, seen in mitral stenosis or chronic HF 1

2. Excluding Alternative Diagnoses

The chest X-ray is critical for ruling out non-cardiac causes of dyspnea that mimic HFpEF:

• Pulmonary disease - emphysema, pulmonary embolism (hyperlucent lung fields) 1
• Pulmonary infection - pneumonia may be secondary to congestion or a primary cause 1
• Pulmonary infiltration - suggests systemic disease requiring separate workup 1
• Normal pulmonary findings - makes pulmonary congestion unlikely and prompts reconsideration of the diagnosis 1

3. Detecting Structural Cardiac Abnormalities

While echocardiography is the primary modality for structural assessment, chest X-ray provides supportive information:

• Cardiomegaly - suggests dilated chambers or ventricular hypertrophy, though can be absent even in chronic HF 1
• Left atrial enlargement - indirect evidence of chronically elevated filling pressures

Critical Caveats for HFpEF

HFpEF presents unique diagnostic challenges on chest X-ray compared to HFrEF: 1

• Findings are typically less pronounced in HFpEF than in reduced EF heart failure
• Cardiomegaly may be absent - patients with HFpEF often have normal-sized or only mildly enlarged hearts with preserved chamber dimensions 3
• Normal chest X-ray does not exclude HFpEF - particularly in early or well-compensated disease

Integration into Diagnostic Algorithm

The chest X-ray fits into a structured, stepwise diagnostic approach: 4

1. Basic assessment - history, physical exam, ECG, natriuretic peptides, and chest X-ray
2. Echocardiography - follows to assess diastolic function and structural abnormalities
3. Advanced testing - reserved for diagnostic uncertainty after initial workup

The chest X-ray should be obtained in two planes (posterior-anterior and lateral) to maximize detection of cardiomegaly, pulmonary congestion, and pleural effusions. 1

Clinical Decision-Making Based on Findings

If Chest X-Ray Shows Congestion:

• Supports diagnosis of HFpEF when combined with symptoms, preserved EF ≥50%, and elevated natriuretic peptides 2
• Proceed with echocardiography to assess diastolic function and structural abnormalities
• Consider treatment for acute decompensation if clinically indicated

If Chest X-Ray is Normal:

• Does not exclude HFpEF, particularly in compensated outpatients 1
• Increases suspicion for non-cardiac causes of dyspnea 1
• Still proceed with echocardiography if clinical suspicion remains high based on symptoms, exam findings, and elevated natriuretic peptides

If Alternative Pathology Detected:

• Pulmonary disease findings warrant spirometry, CT chest, or pulmonary consultation 1
• Infectious infiltrates require treatment of both infection and HF if both present 1

Practical Limitations

The chest X-ray has poor sensitivity and specificity when used in isolation for HFpEF diagnosis. 5 It must be interpreted in the clinical context alongside:

• Framingham criteria (major: orthopnea, JVD, rales, S3 gallop, pulmonary edema, cardiomegaly) 2
• Natriuretic peptides (BNP >35 pg/mL ambulatory, >100 pg/mL hospitalized) 2
• Echocardiographic evidence of diastolic dysfunction 1

Bottom line: The chest X-ray remains an essential, cost-effective first-line imaging test that provides critical information about pulmonary congestion and alternative diagnoses, but it cannot stand alone in diagnosing HFpEF and must be integrated with clinical assessment, biomarkers, and echocardiography. 1, 5