What does a chest X‑ray show in pericarditis?

Chest X-ray Findings in Pericarditis

Chest X-ray in pericarditis is often normal or nonspecific, but may reveal an enlarged cardiac silhouette (if significant effusion is present), pericardial calcifications (particularly in chronic/constrictive disease), or associated findings like pleural effusion or pulmonary pathology. 1

Key Radiographic Findings

In Acute Pericarditis

• Frequently normal: Many patients with acute pericarditis, especially those with purely fibrinous inflammation, have completely normal chest X-rays 1
• Enlarged cardiac silhouette: When present, suggests pericardial effusion, but this finding is:
  • Moderately sensitive (71%) but poorly specific (41%) 2
  • Not reliably diagnostic on its own
  • Typically requires moderate to large effusion (>250-300 mL) to be visible
  • May appear as a "globular" or "water bottle" heart shape 3

Specific Signs to Look For

Pericardial fat stripe (visible pericardium):

• Highly specific (94%) but poorly sensitive (12%) 2
• Appears as a curvilinear density at the extreme margin of the cardiac silhouette
• Best seen on lateral views 1
• More associated with moderate to large effusions 2

Predominant left-sided pleural effusion:

• Highly specific (100%) but poorly sensitive (20%) 2
• Strongly associated with pericardial effusions of all sizes (odds ratio 1.3-7.7) 2
• When present, should raise suspicion for pericardial disease

Pericardial calcifications:

• Appear as curvilinear densities, particularly visible on lateral views 1
• Suggest chronic or constrictive pericarditis 4, 5
• Present in <25% of constrictive pericarditis cases 4
• Important caveat: Presence of calcification should prompt further investigation with CT or cardiac MRI, as it may indicate hemodynamically significant constriction 4, 5

Associated Findings

The chest X-ray provides valuable information about:

• Pulmonary pathology: Pneumonia, tuberculosis, lung cancer 1
• Pleural effusions: Often left-sided predominance 2
• Hilar/mediastinal enlargement: May suggest underlying etiology 1

Clinical Limitations

Critical pitfall: Chest X-ray has poor diagnostic accuracy for pericardial effusion and cannot reliably confirm or exclude pericarditis 2. The 2015 ESC Guidelines explicitly state that echocardiography and CT provide "much greater accuracy" than chest X-ray for assessing pericardial disease 1.

When to proceed beyond chest X-ray:

• Echocardiography is the first-line imaging test for suspected pericardial disease, not chest X-ray 1
• CT or cardiac MRI should be obtained when:
  • Pericardial calcification is detected 4, 5
  • Clinical suspicion remains high despite normal chest X-ray 1
  • Constrictive physiology is suspected 4, 5

Practical Approach

Use chest X-ray as a screening tool that may:

1. Detect incidental findings suggesting pericarditis (calcification, effusion)
2. Identify alternative diagnoses (pneumonia, malignancy)
3. Provide baseline cardiac size for comparison

Do not rely on chest X-ray alone to diagnose or exclude pericarditis. A normal chest X-ray does not rule out clinically significant pericardial disease. Proceed directly to echocardiography when pericarditis is suspected clinically 1.