What are the diagnostic criteria for pericarditis in a male patient aged 20-50 years with suspected pericarditis?

Diagnostic Criteria for Pericarditis

Acute pericarditis is diagnosed when at least 2 of the following 4 criteria are present: pericarditic chest pain, pericardial friction rub, new widespread ST-elevation or PR depression on ECG, or new/worsening pericardial effusion. 1, 2

Core Diagnostic Criteria (Need ≥2 of 4)

1. Pericarditic Chest Pain

• Sharp, pleuritic, retrosternal pain that worsens with inspiration and lying supine 2
• Improves when sitting forward or leaning forward 2
• Present in approximately 90% of cases 3

2. Pericardial Friction Rub

• Highly specific auscultatory finding representing friction between inflamed pericardial layers 2, 4
• Transient in nature, reported in 18% to 84% of patients 4
• Present in less than 30% of acute pericarditis cases 3

3. ECG Changes

• New widespread ST-segment elevation (concave upward) or PR depression in multiple leads 1, 2
• Critical caveat: ECG changes occur in only 25-60% of cases, so their absence does not exclude pericarditis 5
• Typical lead involvement includes I, II, aVL, aVF, and V3-V6 5
• PR elevation in aVR with PR depression in other leads 5
• The ECG reflects epicardial inflammation, not pericardial inflammation itself, since the parietal pericardium is electrically inert 1, 5

4. Pericardial Effusion

• New or worsening fluid collection detected on echocardiography 1, 2
• Present in approximately 60% of cases, most often small 3

Mandatory Initial Workup (All Patients)

Every patient with suspected pericarditis requires the following first-level evaluation: 1, 2

• Auscultation for pericardial rub 1
• ECG to assess for characteristic changes 1, 2
• Transthoracic echocardiography to detect effusion and assess for tamponade 1, 2, 4
• Chest X-ray (often normal unless effusion exceeds 300 mL) 1, 2
• Blood tests: 1, 2
  • Complete blood count with differential
  • Inflammatory markers (CRP and/or ESR)
  • Cardiac biomarkers (troponin, CK) to evaluate for myocardial involvement
  • Renal and liver function tests

Additional Supporting Findings

• Elevated inflammatory markers (CRP, ESR, white blood cell count) are common and help monitor disease activity 1, 2
• Elevated cardiac biomarkers (troponin detectable in 49% of cases with ST elevation) indicate concomitant myocarditis rather than excluding pericarditis 5
• Advanced imaging (CT or CMR) is recommended as second-level testing when first-level evaluation is insufficient 1, 2

Risk Stratification for Triage

Major high-risk features requiring hospital admission and full etiological workup: 1, 2

• Fever >38°C (100.4°F) 1, 6, 3
• Subacute course (symptoms developing over days to weeks) 1, 6
• Large pericardial effusion (diastolic echo-free space >20 mm) 1, 6
• Cardiac tamponade 1, 6
• Failure to respond to aspirin or NSAIDs within 7 days 1, 2, 6

Minor high-risk features: 1

• Pericarditis associated with myocarditis
• Immunosuppression
• Trauma
• Oral anticoagulant therapy

Patients without these risk factors can be safely managed as outpatients with empiric anti-inflammatory therapy. 1, 2

When to Pursue Advanced Diagnostics

Pericardiocentesis or surgical drainage is indicated for: 1, 2

• Cardiac tamponade
• Suspected bacterial or neoplastic pericarditis
• Symptomatic moderate to large effusions not responding to medical therapy

Pericardial fluid analysis should include: 1, 2

• Cytology with cell count
• PCR for tuberculosis
• Aerobic and anaerobic cultures

Common Diagnostic Pitfalls

• Normal inflammatory markers do not exclude pericarditis, especially if the patient is already on anti-inflammatory treatment 2
• Absence of ECG changes occurs in 40% of cases and should not be used to rule out the diagnosis 2, 5
• Elevated troponin indicates myopericarditis, not a contraindication to diagnosis 2, 5
• Distinguish from acute coronary syndrome: Pericarditis shows concave ST elevation without reciprocal changes, while MI shows convex ST elevation with reciprocal depression 5