What is the initial workup for a patient with suspected pericarditis?

Initial Workup for Suspected Pericarditis

All patients with suspected pericarditis require a first-level diagnostic evaluation consisting of: ECG, transthoracic echocardiography, chest X-ray, and blood tests including inflammatory markers (CRP and/or ESR), complete blood count with differential, cardiac biomarkers (troponin, CK), and renal/liver/thyroid function tests. 1

Diagnostic Criteria

The diagnosis requires at least 2 of the following 4 criteria 1, 2:

• Pericarditic chest pain: Sharp, pleuritic, retrosternal pain that worsens with inspiration and improves when sitting forward (present in ~90% of cases) 1, 3, 4
• Pericardial friction rub: Auscultatory finding at the left lower sternal border (present in <30% of cases) 1, 3, 5
• New widespread ST-elevation or PR depression on ECG: Seen in 25-50% of cases 1, 3, 4
• New or worsening pericardial effusion: Detected on echocardiography (present in ~60% of cases) 1, 3

First-Level Testing (Mandatory for All Cases)

Physical Examination

• Auscultation for pericardial friction rub at the left lower sternal border 1, 6

Laboratory Tests

• Inflammatory markers: CRP and/or ESR, white blood cell count with differential 1, 7
• Cardiac biomarkers: Troponin and creatine kinase (CK) to assess for myocardial involvement 1, 7
• Renal function tests, liver function tests, and thyroid function tests 1, 7

Imaging Studies

• 12-lead ECG: Look for widespread ST-elevation with upward concavity and PR depression 1, 5
• Transthoracic echocardiography: Assess for pericardial effusion, cardiac tamponade, and ventricular function 1, 6
• Chest X-ray: Identify cardiomegaly (requires >300 mL effusion) and pleuro-pulmonary involvement 1, 6

Risk Stratification

Immediately assess for high-risk features that mandate hospital admission and further workup 1, 6:

Major Risk Factors (require hospitalization)

• Fever >38°C (>100.4°F) 1
• Subacute course (symptoms developing over days/weeks without clear acute onset) 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 (consider hospitalization)

• Myopericarditis (troponin elevation) 6
• Immunosuppression 6
• Trauma 6
• Oral anticoagulant therapy 6

Second-Level Testing (For High-Risk Patients or Diagnostic Uncertainty)

Advanced Imaging

• Cardiac MRI (CMR): Preferred advanced imaging modality with 94-100% sensitivity for detecting pericardial inflammation; can distinguish acute myopericarditis from other cardiomyopathies 1, 2
• Cardiac CT with IV contrast (not CT angiography): Reasonable alternative when MRI is contraindicated or unavailable; shows pericardial thickening/enhancement with 54-59% sensitivity and 91-96% specificity 1, 2

Etiologic Workup for High-Risk Patients

For suspected autoimmune disease 1:

• ANA, ENA, ANCA
• Ferritin (if Still's disease suspected)
• ACE and 24-hour urinary calcium (if sarcoidosis suspected)
• Consider PET scan for large vessel arteritis or sarcoidosis

For suspected tuberculosis 1:

• IGRA test (Quantiferon, ELISpot)
• Chest CT scan

For suspected neoplasm 1:

• Chest and abdomen CT scan
• Consider PET scan

For suspected viral infection 1:

• PCR for viral genomes (preferred over serology)
• Serology for HCV and HIV

For suspected bacterial infection 1:

• Blood cultures before antibiotics
• Serology for Coxiella burnetii (Q-fever) or Borrelia if clinically indicated

Invasive Procedures (Specific Indications Only)

Pericardiocentesis or surgical drainage indicated for 1:

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

Pericardial fluid analysis should include 1:

• Cytology with cell count
• PCR for tuberculosis
• Mycobacterial cultures, aerobic and anaerobic cultures

Common Pitfalls and Caveats

• ECG changes may be absent in up to 40% of cases, so normal ECG does not exclude pericarditis 2, 4
• Pericardial friction rub is present in <30% of cases and is often transient 1, 3
• Troponin elevation (occurs in ~27% of cases) indicates myopericarditis, not worse prognosis 2, 4
• Normal inflammatory markers do not exclude pericarditis, especially if patient is already on anti-inflammatory treatment 2, 7
• Do not order CT angiography for pericarditis evaluation; the appropriate CT protocol is cardiac CT with IV contrast 2
• Chest X-ray is typically normal unless effusion exceeds 300 mL 1, 6
• Low-risk patients can be managed as outpatients with empiric anti-inflammatory therapy and 1-week follow-up to assess treatment response 1