How Pericarditis is Diagnosed
Pericarditis is diagnosed clinically when you have at least 2 of 4 specific criteria: pericarditic chest pain, pericardial friction rub, new widespread ST-elevation or PR depression on ECG, or new/worsening pericardial effusion 1.
The Diagnostic Criteria
According to the 2015 ESC Guidelines, the diagnosis requires meeting at least 2 of these 4 criteria 1:
- Pericarditic chest pain - Sharp, pleuritic pain that worsens when lying supine (present in ~90% of cases) 2
- Pericardial friction rub on auscultation (present in <30% of cases) 2
- New widespread ST-elevation or PR depression on ECG (seen in 25-50% of cases, though typical ECG changes occur in up to 60%) 1, 2
- Pericardial effusion - New or worsening fluid around the heart (present in ~60%, most often small) 1, 2
Required Diagnostic Workup
Every patient with suspected pericarditis must undergo 1:
- ECG (Class I recommendation)
- Transthoracic echocardiography (Class I recommendation)
- Chest X-ray (Class I recommendation)
- Inflammatory markers: CRP, ESR, white blood cell count (Class I recommendation)
- Cardiac injury markers: CK, troponin (Class I recommendation)
Important Diagnostic Nuances
The ECG changes imply inflammation of the epicardium, not the pericardium itself (which is electrically inert) 1. The major differential diagnosis you must exclude is acute coronary syndrome with ST-elevation 1.
Elevated troponin doesn't rule out pericarditis—it suggests concomitant myopericarditis, which changes management slightly but still follows similar treatment principles 1.
Common Pitfall: The Friction Rub
A pericardial friction rub can be mimicked by other conditions. One case report describes an anterior mediastinal mass compressing the right ventricular outflow tract that produced a coarse outflow murmur convincingly mimicking a pericardial friction rub 3. This highlights why the multi-criteria approach is essential—never diagnose based on a single finding.
Who Makes the Diagnosis
The diagnosis is typically made by:
- Emergency department physicians (pericarditis accounts for up to 5% of ED visits for nonischemic chest pain) 2
- Cardiologists
- Primary care physicians in outpatient settings for low-risk presentations
Low-risk patients without high-risk features can be diagnosed and managed as outpatients with empiric anti-inflammatory therapy and 1-week follow-up 1.