What is the initial diagnostic and treatment approach for a patient suspected of having pericarditis?

Diagnosis and Initial Management of Pericarditis

Diagnostic Criteria

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, and new or worsening pericardial effusion. 1, 2

Clinical Features to Identify

• Chest pain: Sharp, pleuritic, retrosternal pain that worsens with inspiration and improves when sitting forward or leaning forward 2, 3
• Pericardial friction rub: Highly specific auscultatory finding representing friction between inflamed pericardial layers, though present in only 18-84% of cases and often transient 2, 4
• ECG changes: New widespread ST-segment elevation (concave upward) or PR depression in multiple leads without reciprocal changes 1, 2, 4
• Pericardial effusion: New or worsening fluid collection detected on imaging 1, 2

First-Level Diagnostic Workup (All Patients)

Every patient with suspected pericarditis requires the following initial evaluation: 1

• Auscultation for pericardial friction rub 1, 5
• ECG to identify characteristic changes 1
• Transthoracic echocardiography to detect effusion, assess size, and evaluate for tamponade 1, 2
• Chest X-ray (though typically normal unless effusion exceeds 300 mL) 1
• Blood tests including:
  • Complete blood count with differential 1, 6
  • Inflammatory markers: CRP and/or ESR 1, 6
  • Cardiac injury markers: troponin and CK 1, 6
  • Renal and liver function tests 1, 6
  • Thyroid function tests 1, 6

Important Caveats

• ECG changes may be absent in up to 40% of cases 2
• Troponin elevation indicates concomitant myocarditis (myopericarditis), not primary pericardial disease 1, 2
• Normal inflammatory markers do not exclude pericarditis, especially if anti-inflammatory treatment already started 2, 6

Risk Stratification for Triage

Patients with any of the following high-risk features require hospital admission for etiologic workup and monitoring: 1, 5

Major Risk Factors

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

Minor Risk Factors

• Myopericarditis 1, 5
• Immunosuppression 1, 5
• Trauma 1, 5
• Oral anticoagulant therapy 1, 5

Low-risk patients without these features can be managed as outpatients with empiric anti-inflammatory therapy and follow-up within 1 week to assess treatment response. 1

Second-Level Testing (High-Risk Patients or Unclear Diagnosis)

Cardiac MRI is the preferred advanced imaging modality when echocardiography is nondiagnostic or diagnostic uncertainty exists, with 94-100% sensitivity for detecting pericardial inflammation. 2, 5

• CT with IV contrast (not CT angiography) is reserved for when MRI is contraindicated/unavailable or when evaluating for pericardial calcification in suspected constrictive pericarditis 2
• Pericardiocentesis or surgical drainage is indicated for: cardiac tamponade, suspected bacterial or neoplastic pericarditis, or symptomatic moderate-to-large effusions not responding to medical therapy 1, 5

Etiologic Testing in High-Risk Patients

For suspected autoimmune disease: ANA, ENA, ANCA, ferritin (if Still's disease suspected), ACE and 24-hour urinary calcium (if sarcoidosis suspected) 1, 6

For suspected tuberculosis: IGRA test (Quantiferon, ELISpot), chest CT scan 1, 6

For suspected neoplasm: Chest and abdomen CT scan, consider PET 1

For suspected viral infection: PCR for viral genomes (preferred over serology), serology for HCV and HIV 1, 6

For suspected bacterial infection: Blood cultures before antibiotics, serology for Coxiella burnetii (Q fever) or Borrelia (Lyme disease) 1, 6

Initial Treatment Approach

First-line therapy consists of high-dose NSAIDs (or aspirin if post-MI pericarditis) plus colchicine for 3 months, with NSAIDs tapered once chest pain resolves and CRP normalizes. 5, 3, 7

• Colchicine reduces recurrence risk from 37.5% to 16.7% (absolute risk reduction 20.8%) and should be continued for at least 3 months 3, 7
• Corticosteroids are NOT first-line therapy due to increased recurrence risk; reserved for patients with contraindications to NSAIDs/colchicine, autoimmune disorders, or first recurrence failing NSAIDs/colchicine 5, 7
• Response to therapy should be evaluated after 1 week 1

Common Pitfalls to Avoid

• Do not order CT angiography for pericarditis evaluation; the appropriate CT protocol is cardiac CT with IV contrast 2
• Do not use corticosteroids as first-line therapy unless specific contraindications exist 5, 7
• Do not assume normal inflammatory markers exclude pericarditis 2, 6
• Do not delay pericardiocentesis in cardiac tamponade 1, 5