What are the characteristics and treatment of acute pericarditis?

Characteristics and Treatment of Acute Pericarditis

Acute pericarditis is characterized by sharp, pleuritic chest pain that radiates to the trapezius ridge, varies with posture (worsens when supine and improves when sitting forward), and may simulate ischemic pain. This distinctive chest pain pattern, along with other diagnostic criteria, helps differentiate it from other cardiac conditions 1.

Diagnostic Criteria

Diagnosis requires at least 2 of the following 4 criteria:

• Pericarditic chest pain - Retrosternal or left precordial, sharp, pleuritic pain that radiates to the trapezius ridge and varies with posture (improves when sitting forward) 1
• Pericardial friction rub - Mono-, bi-, or triphasic sound on auscultation, which can be transient and is present in <30% of cases 1
• ECG changes - New widespread ST-segment elevation (concave upward) and PR-segment depression, occurring in 25-50% of cases 1, 2
• Pericardial effusion - New or worsening effusion seen on echocardiography 1

Supporting Findings

• Elevated inflammatory markers (CRP, ESR, white blood cell count) 1
• Fever, malaise, and myalgia may precede chest pain (common prodrome) 1
• Heart rate is usually rapid and regular 1
• Chest X-ray is typically normal unless pericardial effusion exceeds 300 ml 1

Risk Stratification

High-risk features requiring hospital admission include:

• High fever (>38°C/100.4°F) 1
• Subacute onset (symptoms developing over several days) 1
• Large pericardial effusion (>20 mm on echocardiography) 1
• Cardiac tamponade 1
• Failure to respond to NSAIDs within 7 days 1
• Elevated cardiac biomarkers suggesting myopericarditis 1

Treatment Algorithm

First-Line Treatment (for low-risk patients)

• NSAIDs at full anti-inflammatory doses until symptom resolution 1
  • Aspirin 750-1000 mg every 8 hours for 1-2 weeks, then taper
  • Ibuprofen 600-800 mg every 8 hours for 1-2 weeks, then taper
• Colchicine (0.5 mg twice daily or 0.5 mg daily for patients <70 kg) for 3 months to reduce recurrence risk 1, 2
• Exercise restriction until symptom resolution and CRP normalization 1
• Follow-up evaluation after 1 week to assess treatment response 1

Second-Line Treatment

• Low-dose corticosteroids (only if contraindications to NSAIDs/colchicine exist or after excluding infectious causes) 1
  • Prednisone 0.25-0.50 mg/kg/day with gradual tapering 1
  • Avoid higher doses except in special cases 1

For Recurrent Pericarditis

• Continue first-line therapy with NSAIDs and colchicine (extended to at least 6 months) 1, 2
• For corticosteroid-dependent cases not responsive to colchicine, consider:
  • IV immunoglobulins, anakinra, or azathioprine 1
  • Pericardiectomy as last resort after failed medical therapy 1

Important Considerations and Pitfalls

• Avoid glucocorticoids as first-line therapy - They increase risk of recurrence and should be reserved for specific indications 1
• Avoid NSAIDs in post-myocardial infarction pericarditis - May impair myocardial healing 1
• Monitor for complications - Cardiac tamponade (<3%) and constrictive pericarditis (<0.5%) are rare but life-threatening 2
• Echocardiography is essential - To detect effusion and evaluate for complications 1
• Taper medications gradually - Only after symptoms resolve and CRP normalizes 1
• Differentiate from acute coronary syndrome - ECG in pericarditis shows widespread ST elevation without reciprocal changes 1, 3

Most cases of acute pericarditis in North America and Western Europe are idiopathic or viral in origin and have a favorable prognosis with appropriate treatment 2, 3. However, 15-30% of patients may experience recurrence, requiring longer treatment courses 2.