How to diagnose pericarditis in Systemic Lupus Erythematosus (SLE)?

Diagnosing Pericarditis in Systemic Lupus Erythematosus (SLE)

Diagnosis of pericarditis in SLE requires at least 2 of 4 criteria: pericarditic chest pain, pericardial rubs, new widespread ST-elevation or PR depression on ECG, and pericardial effusion (new or worsening). 1

Diagnostic Approach

Clinical Presentation

• Pericarditis is the most common cardiac manifestation in SLE, occurring in up to 50% of cases 2
• Key symptoms to evaluate:
  • Retrosternal or left precordial chest pain (radiating to trapezius ridge)
  • Pleuritic pain that varies with posture
  • Shortness of breath
  • Fever, malaise, and myalgia (common prodromal symptoms)
  • Low-grade fever 3

Physical Examination

• Listen for pericardial friction rub (may be mono-, bi-, or triphasic)
• Note that friction rub can be transient and may be missed 1
• Assess for signs of cardiac tamponade if severe:
  • Tachycardia
  • Hypotension
  • Pulsus paradoxus
  • Jugular venous distention

Diagnostic Tests

1. ECG (Class I recommendation) 1, 4

   • Look for:
     • Widespread ST-segment elevation (concave upward) in multiple leads
     • PR segment depression (except in aVR where PR elevation may occur)
     • ST-segment depression in lead aVR
   • Typical ECG evolution in 4 stages:
     • Stage I: Anterior and inferior concave ST elevation with PR depression
     • Stage II: ST junctions return to baseline, PR remains deviated
     • Stage III: T waves progressively flatten and invert
     • Stage IV: ECG returns to pre-pericarditis state

2. Transthoracic Echocardiography (Class I recommendation) 1

   • Essential to detect:
     • Pericardial effusion
     • Signs of tamponade
     • Concomitant myocardial dysfunction
   • Should be performed periodically in SLE patients 2

3. Laboratory Tests (Class I recommendation) 1

   • Inflammatory markers:
     • C-reactive protein (CRP)
     • Erythrocyte sedimentation rate (ESR)
     • White blood cell count
   • Cardiac injury markers:
     • Creatine kinase (CK)
     • Troponin (to identify possible myopericarditis)
   • SLE-specific markers:
     • Complement levels (may be low in active SLE) 3
     • Anti-dsDNA antibodies
     • Complete blood count (may show cytopenias) 3

4. Chest X-ray (Class I recommendation) 1

   • May range from normal to "water bottle" heart shadow
   • Cardiomegaly visible only with effusions >300 ml
   • Look for calcified pericardium in chronic cases 3
   • Check for associated pleural effusion 3

5. Advanced Imaging (Class IIa recommendation) 1, 4

   • Cardiac MRI:
     • Provides detailed assessment of pericardial inflammation
     • Evaluates myocardial involvement
   • Chest CT:
     • Evaluates pericardial thickness and calcification
     • May detect localized pericarditis missed by echocardiography 5
     • Particularly useful in SLE when standard tests are negative

6. Pericardiocentesis (Class I recommendation in tamponade, Class IIa in large/recurrent effusions) 1

   • Indicated for:
     • Cardiac tamponade
     • Large or recurrent effusions
     • Suspected infectious or malignant etiology
   • Analysis should include:
     • Culture for bacteria, fungi, and mycobacteria 3
     • Cytology
     • PCR for infectious agents

Special Considerations in SLE

• Pericarditis may be the initial manifestation of SLE in some patients 6
• Localized pericarditis can occur in SLE and may be missed by standard echocardiography 5
• Always exclude infectious causes before attributing pericarditis to SLE activity 3
• Monitor for rare but serious complications:
  • Constrictive pericarditis
  • Cardiac tamponade 3

Diagnostic Pitfalls to Avoid

• Relying solely on ECG changes for diagnosis (present in only 60% of cases) 1
• Missing localized pericarditis that may require CT imaging 5
• Failing to differentiate from acute coronary syndrome:
  • Pericarditis: diffuse ST elevation without reciprocal ST depression
  • ACS: localized ST elevation with reciprocal changes 4
• Overlooking pericarditis in SLE patients with atypical presentation or without audible friction rub 5

By following this structured diagnostic approach, clinicians can effectively identify and manage pericarditis in SLE patients, leading to improved outcomes and reduced complications.