Tuberculous pericarditis

Background

• A form of pericarditis caused by Mycobacterium tuberculosis
• Thought to enter the pericardium via retrograde lymphatic spread or hematogenous spread, rarely through direct invasion from adjacent tissue
• Organised into four stages:
  • Stage 1: Dry stage, with a fibrinous exudate
  • Stage 2: Effusive stage (most common at diagnosis), with a lymphocytic and often blood-stained exudate
  • Stage 3: Adsorptive stage, with resolution of the effusion and more organized granulomatous inflammation of the pericardium
  • Stage 4: Constrictive stage, with scarring of the pericardium leading to a constrictive pericarditis

Clinical Manifestations

• Varies by stage:
  • Stage 1 (dry stage): similar to acute pericarditis from other causes, with chest pain, pericardial rub, and widespread ST changes, without effusion
  • Stage 2 (effusive stage):
    • Most common stage at diagnosis
    • Heart failure or cardiac tamponade due to large effusion
    • May have concomitant constrictive pericarditis (may become more obvious after pericardiocentesis)
  • Stage 3 (adsorptive stage): similar to other causes of constrictive pericarditis, and will have thick, fibrinous fluid on imaging
  • Stage 4 (constrictive stage): similar to other causes of constrictive pericarditis, though with no residual fluid on imaging

Investigations

• May be seen on chest x-ray, echo, cardiac MRI, or CT chest
  • Often see mediastinal lymphadenopathy on CT chest (unlike viral causes of pericarditis, though no different from malignant ones)
• Pericardiocentesis is ideally done when effusion greater than 1 cm
  • Provides therapeutic and diagnostic benefit
  • Fluid analysis typically shows protein-rich lymphocytic exudate that is often macroscopically blood-stained
  • ADA has reasonable sensitivity but is not specific
  • Mycobacterial culture are not particularly sensitive (50-75% sensitive)
• Pericardial biopsy is the most definitive, but also most challenging to acquire and still has relatively unimpressive culture sensitivity

Management

• Generally treated with 6 months of first-line TB treatment
• The benefits of adjunctive steriods are unclear, but may decrease mortality, and are conditionally recommended for HIV-negative adults
  • Prednisolone 120 mg p.o. daily for 1 week, followed by 90 mg for 1 week, 60 mg for 1 week, 30 mg for 1 week, 15 mg for 1 week, and 5 mg for 1 week

Further Reading

• Tuberculous Pericarditis. Circulation. 2005;112(23):3608-3616. doi: 10.1161/CIRCULATIONAHA.105.543066
• Chapter 7: Extra-pulmonary tuberculosis. Canadian Tuberculosis Standards, 8th edition. 2022. https://www.canada.ca/en/public-health/services/diseases/tuberculosis/health-professionals/canadian-tuberculosis-standards/extra-pulmonary-tuberculosis.html