How to diagnose pericarditis?

Diagnosing Pericarditis

The diagnosis of pericarditis requires at least two of the following criteria: characteristic pleuritic chest pain, pericardial friction rub, new or worsening pericardial effusion, or specific electrocardiographic changes (widespread ST elevations or PR depressions). 1, 2

Diagnostic Criteria

Pericarditis diagnosis is based on a combination of:

1. Clinical presentation:

   • Chest pain (typically sharp, pleuritic, improves when leaning forward)
   • Pericardial friction rub (highly specific but transient, present in 18-84% of cases)

2. Electrocardiographic findings:

   • PR-segment depressions
   • Diffuse, concave, upward ST-segment elevations without reciprocal changes
   • T-wave inversions in later stages

3. Imaging evidence:

   • New or worsening pericardial effusion on echocardiography

4. Laboratory markers:

   • Elevated inflammatory markers (CRP, ESR, WBC)
   • Cardiac biomarkers (to assess for myocardial involvement)

Diagnostic Workup

The European Society of Cardiology recommends a systematic two-level approach 1:

Level 1 (Basic) - For All Patients:

• Electrocardiogram (ECG): Look for characteristic changes
• Transthoracic echocardiography: Evaluate for pericardial effusion and rule out cardiac tamponade
• Laboratory tests:
  • Inflammatory markers: C-reactive protein (CRP), erythrocyte sedimentation rate (ESR), white blood cell count with differential
  • Cardiac injury markers: Troponin I/T, creatine kinase (CK-MB)
  • Renal function and liver tests
  • Thyroid function tests

Level 2 (Advanced) - For High-Risk Patients:

Indicated for patients with:

• Fever >38°C
• Subacute course
• Large pericardial effusion
• Cardiac tamponade
• Immunocompromised status
• Failure to respond to NSAIDs

Advanced investigations include:

• Cardiac MRI (CMR): Provides detailed assessment of pericardial inflammation and myocardial involvement
• Chest CT: Evaluates pericardial thickness and calcification
• Pericardiocentesis: Indicated for cardiac tamponade, suspected bacterial or neoplastic pericarditis, or symptomatic moderate to large effusions not responding to medical therapy

Myopericardial Involvement

When troponin elevation is present, the condition is classified as myopericarditis 1:

• Requires differentiation from acute coronary syndromes
• Patients with myopericarditis should be hospitalized for diagnosis and monitoring
• Consider cardiac MRI to confirm myocardial involvement
• Coronary angiography may be warranted to rule out acute coronary syndromes in patients with significant troponin elevation

Risk Stratification

Patients with the following features should be considered for hospitalization 2, 3:

• Fever
• Elevated inflammatory markers
• Pericardial effusion
• Subacute course
• Failure to respond to initial therapy
• Immunocompromised status

Common Pitfalls and Caveats

1. Misdiagnosis: Pericarditis can mimic acute coronary syndrome. Key differentiating features include:

   • Widespread rather than localized ST elevation
   • Absence of reciprocal changes
   • PR depression (not typically seen in MI)

2. Incomplete evaluation: Always perform echocardiography to assess for effusion and potential complications 1, 2

3. Overlooking myocardial involvement: Always check cardiac biomarkers to identify possible myopericarditis 1

4. Failure to identify specific etiologies: While most cases in developed countries are idiopathic/viral (80-90%), consider other causes like tuberculosis (common in developing countries), autoimmune diseases, cancer, and post-cardiac injury syndromes 4

5. Underestimating complications: Be vigilant for signs of cardiac tamponade or constriction, especially in high-risk patients 5

By following this systematic approach to diagnosis, clinicians can accurately identify pericarditis and its complications, leading to appropriate management and improved outcomes.