What is the diagnostic approach and initial treatment for pericarditis?

Diagnosis of Pericarditis

Diagnose acute pericarditis when at least 2 of 4 clinical 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

Clinical Diagnostic Criteria

The diagnosis requires meeting at least 2 of these 4 cardinal features 1, 2:

• Pericarditic chest pain: Sharp, retrosternal, pleuritic pain that worsens with inspiration and improves when sitting forward 2
• Pericardial friction rub: Auscultatory finding from friction between inflamed pericardial layers, though highly specific it is transient and present in only 18-84% of cases 2, 3
• ECG changes: New widespread ST-segment elevation or PR depression in multiple leads, though absent in up to 40% of cases 1, 2
• Pericardial effusion: New or worsening fluid collection detected by imaging 1, 2

First-Level Diagnostic Workup (Required for All Cases)

Perform these tests in every patient with suspected pericarditis 1, 2:

• Auscultation for pericardial rub 1
• ECG: Look for diffuse, concave upward ST-elevations and PR depressions without reciprocal changes 1, 3
• Transthoracic echocardiography: Assess for effusion size and complications 1, 3
• Chest X-ray: Usually normal unless effusion exceeds 300 mL 1, 2
• Blood tests 1, 4:
  • Complete blood count with differential
  • Inflammatory markers (CRP and/or ESR)
  • Cardiac biomarkers (troponin, CK) to detect myocardial involvement
  • Renal and liver function tests
  • Thyroid function tests

Important Caveat on Laboratory Findings

Elevated cardiac biomarkers indicate concomitant myocarditis rather than excluding pericarditis, and normal inflammatory markers do not rule out pericarditis, especially if the patient is already on anti-inflammatory treatment. 2, 4

Risk Stratification for Disposition and Further Testing

High-Risk Features Requiring Hospital Admission 1, 2, 5

Admit patients with any of these major risk factors for full etiological workup 1, 5:

• Fever >38°C 1, 5
• Subacute course (symptoms developing over days to weeks) 1, 5
• Large pericardial effusion (diastolic echo-free space >20 mm) 1
• Cardiac tamponade 1, 5
• Failure to respond to aspirin/NSAIDs within 7 days 1, 5

Low-Risk Patients

Patients without high-risk features can be managed as outpatients with empiric anti-inflammatory therapy without extensive diagnostic evaluation. 1, 2, 6

Second-Level Testing (For High-Risk Patients)

Advanced Imaging 1

• CT and/or cardiac MRI: Recommended as second-level testing to assess pericardial thickness, calcifications, and extent of involvement 1

Invasive Procedures 1

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 (When Obtained) 1

Perform these tests on pericardial fluid 1:

• Cytology: Cell count and differential
• PCR: For tuberculosis and viral pathogens
• Microbiology: Mycobacterium cultures, aerobic and anaerobic cultures

Etiology-Specific Testing in High-Risk Patients 1, 4

Based on clinical suspicion 1, 4:

• Autoimmune: ANA, ENA, ANCA, ferritin (if Still's disease suspected)
• Tuberculosis: IGRA test (Quantiferon, ELISpot), chest CT scan
• Neoplasm: Chest and abdomen CT scan, consider PET
• Viral: PCR for viral genomes, serology for HCV and HIV
• Bacterial: Blood cultures before antibiotics, serology for Coxiella burnetii if Q-fever suspected

Initial Treatment Approach

First-Line Therapy for Idiopathic/Viral Pericarditis 1, 2, 3, 7

NSAIDs are the mainstay of first-line therapy, with colchicine added as adjunctive treatment to reduce recurrence risk. 1, 2, 3, 7

• NSAIDs: High-dose therapy tapered once chest pain resolves and CRP normalizes, typically over several weeks 3, 7, 8
• Colchicine: 0.5 mg twice daily (or once daily for patients <70 kg or intolerant to higher doses) for 3 months in acute pericarditis, 6 months for recurrent pericarditis 1, 7, 8

Critical Treatment Principle

Corticosteroids are NOT recommended as first-line therapy for acute pericarditis and are contraindicated in confirmed viral pericarditis. 1, 2, 7 Reserve corticosteroids only for patients with contraindications to NSAIDs, pregnancy beyond 20 weeks, or systemic inflammatory conditions 3, 7.

Monitoring Treatment Response 1, 2

• Use CRP to guide treatment duration and assess response to therapy 1, 2
• Evaluate response after 1 week—failure to respond is a major risk factor requiring hospitalization 5
• Restrict physical activity until symptoms resolve and CRP normalizes; for athletes, restrict competitive sports for at least 3 months 5

Common Pitfalls

• Do not dismiss pericarditis based on absent ECG changes—they occur in only 60% of cases 1, 2
• Do not interpret elevated troponin as excluding pericarditis—it indicates myopericarditis, not a different diagnosis 2, 4
• Do not perform extensive diagnostic workup in low-risk patients—most cases in developed countries are idiopathic/viral with excellent prognosis 1, 6
• Do not use corticosteroids as first-line therapy—they increase recurrence risk and can reactivate viral infections 1, 5, 7