What is the appropriate diagnostic work‑up and first‑line treatment for acute pericarditis in an adult presenting with sharp chest pain that worsens when lying flat and improves when sitting up?

Acute Pericarditis: Diagnosis and Treatment

Diagnostic Criteria

Acute pericarditis is diagnosed when at least 2 of the following 4 criteria are present: sharp, pleuritic chest pain that worsens when supine and improves when sitting forward; pericardial friction rub on auscultation; new widespread ST-segment elevation or PR depression on ECG; and new or worsening pericardial effusion on echocardiography 1.

Clinical Presentation

• Chest pain occurs in approximately 90% of cases and is characteristically sharp, pleuritic, radiates to the left shoulder, worsens when lying flat, and improves when sitting up or leaning forward 1, 2.
• Pericardial friction rub is present in less than 30% of cases but is highly specific when detected 1, 3.

Diagnostic Testing (First-Level Workup)

• 12-lead ECG shows diffuse upward-sloping ST-segment elevation and PR depression in approximately 25-50% of cases 1, 4, 5.
• Transthoracic echocardiography is mandatory to quantify pericardial effusion (present in ~60% of cases), assess for cardiac tamponade, and evaluate ventricular function 4, 1, 3.
• Chest X-ray should be obtained to identify cardiomegaly, pulmonary tuberculosis, or malignancy 4.
• Inflammatory markers including CRP and/or ESR must be measured, as CRP elevation is crucial for guiding treatment duration and assessing therapeutic response 6, 4, 3.
• Cardiac biomarkers (troponin I/T, creatine kinase) should be measured to detect myopericarditis, though normal values do not exclude disease 4, 3.
• Complete blood count with differential to assess for leukocytosis or anemia 4.

Risk Stratification for Hospital Admission

High-risk features mandating hospitalization include: fever >38°C, subacute course (symptoms developing over days to weeks), large pericardial effusion (≥20 mm echo-free space), cardiac tamponade, failure to respond to aspirin or NSAIDs after at least 1 week, immunosuppression, myopericarditis (elevated troponin), or trauma history 4, 3, 1.

Second-Level Workup for High-Risk Patients

• Advanced imaging with CT and/or cardiac MRI should be performed to assess pericardial thickness, detect loculated effusions, and identify mediastinal/tracheobronchial lymphadenopathy 4.
• Pericardiocentesis with fluid analysis is indicated urgently for cardiac tamponade, suspected bacterial pericarditis, suspected neoplastic pericarditis, and symptomatic moderate-to-large effusions not responding to medical therapy 4.

First-Line Treatment

Aspirin or NSAIDs combined with colchicine is the recommended first-line therapy for acute pericarditis (Class I, Level A recommendation). 6

Specific Regimens

• NSAIDs with gastroprotection: Ibuprofen 600-800 mg three times daily or aspirin 750-1000 mg three times daily, with proton pump inhibitor co-administration 6, 7.
• Colchicine as adjunctive therapy: Must be added to aspirin/NSAID therapy to relieve symptoms and reduce recurrence risk from 37.5% to 16.7% (absolute risk reduction 20.8%) 6, 1.
• Colchicine dosing: 0.5 mg twice daily for patients ≥70 kg or 0.5 mg once daily for patients <70 kg, continued for 3 months 6, 1.

Treatment Duration and Monitoring

• Continue therapy until resolution of symptoms and normalization of CRP, typically 1-2 weeks for uncomplicated cases, then taper 6.
• CRP should guide treatment length and assess response to therapy 6.
• Exercise restriction is recommended for non-athletes until resolution of symptoms and normalization of CRP, ECG, and echocardiogram; for athletes, at least 3 months of restriction is required 6.

When NOT to Use Corticosteroids

Corticosteroids are NOT recommended as first-line therapy for acute pericarditis (Class III recommendation) because they increase recurrence rates from 15-30% to 50% after a first recurrence 6, 7.

Limited Indications for Corticosteroids

• Low-dose corticosteroids (prednisone 0.2-0.5 mg/kg/day) should be considered only when aspirin/NSAIDs and colchicine are contraindicated or have failed, when infectious causes have been excluded, or when there is a specific indication such as autoimmune disease 6.

Common Pitfalls to Avoid

• Do not delay pericardiocentesis in cardiac tamponade; vasodilators and diuretics are contraindicated and worsen hemodynamics 4.
• Do not use high-dose corticosteroids (prednisone 1.0 mg/kg/day) as they significantly increase recurrence risk; if corticosteroids are necessary, use low-to-moderate doses 6.
• Do not stop colchicine prematurely; the full 3-month course is essential to prevent recurrence 6, 1.
• Do not overlook tuberculosis in high-risk populations (endemic areas, immunocompromised patients), as it requires specific antituberculous therapy for 6 months 8, 4.
• Do not rely on serology alone for viral pericarditis diagnosis; PCR of pericardial fluid is required for confirmation 4.

Prognosis

Most patients with acute idiopathic or presumed viral pericarditis have a good long-term prognosis, with constrictive pericarditis occurring in <1% of cases 6, 1. However, 15-30% of patients develop recurrent pericarditis, particularly if not treated with colchicine or if treated with corticosteroids 6, 1.