What are the differential diagnoses and management options for pericardial thickness exceeding 5 mm?

Differential Diagnoses for Pericardial Thickness >5 mm

Pericardial thickness exceeding 5 mm is pathologically thickened and most commonly indicates constrictive pericarditis, acute/chronic pericarditis, or post-cardiac surgery changes, though 18% of surgically-proven constrictive pericarditis cases have normal pericardial thickness (<3 mm), so thickness alone cannot exclude constriction. 1, 2

Primary Differential Diagnoses

Constrictive Pericarditis

• Most common cause of significantly thickened pericardium, though normal pericardial thickness (<3 mm) is present in 18% of surgically-proven cases 1, 2
• Thickening typically most pronounced at the base of ventricles (RV>LV), atrioventricular grooves, and atria 1
• May be mild to moderate thickening even in severe constriction 1
• Etiologies include:
  • Post-cardiac surgery (now leading cause in developed countries) 3
  • Prior chest irradiation 2
  • Idiopathic 2, 3
  • Tuberculosis (historically most common, still prevalent in developing countries) 3
  • Post-myocardial infarction 2

Acute Pericarditis

• Thickened pericardial layers with variable pericardial effusion 1
• Strong pericardial late gadolinium enhancement (LGE) on CMR following contrast administration 1
• Pericardial layers enhance after contrast on CT 1
• May show subepicardial/mid-wall myocardial LGE in cases of myopericarditis 1

Transient Constrictive Pericarditis

• Temporary constriction developing with acute inflammatory pericarditis and mild effusion 1
• Resolves with anti-inflammatory therapy within several weeks to 2-3 months 1
• Inflamed pericardium shows enhancement on CT and/or CMR 1
• Elevated CRP and imaging evidence of pericardial inflammation predict reversibility 4

Effusive-Constrictive Pericarditis

• Combination of pericardial effusion with underlying constrictive physiology 1
• Scarred pericardium constricts cardiac volume while putting pericardial fluid under increased pressure 1
• Diagnosed by failure of right atrial pressure to fall by 50% or below 10 mmHg after pericardiocentesis 1

Recurrent Pericarditis

• Possibly heterogeneous distribution of thickening due to adhesions 1
• May develop chronic changes over time 5

Critical Diagnostic Approach

Initial Imaging Assessment

• Normal pericardial thickness is <3.0 mm on CT/CMR and 0.7-2.0 mm on CT specifically 1
• Pericardial width >4 mm on CT/CMR is regarded as abnormal for effusion assessment 1
• Thickness >5 mm is definitively pathologic and warrants comprehensive evaluation 1

Distinguishing Features on Advanced Imaging

CT Findings:

• Most accurate for detecting pericardial calcifications 1
• Contrast enhancement indicates active inflammation 1
• Can assess extent and distribution of thickening 1

CMR Findings (Preferred Modality):

• Normal pericardial thickness ranges 1.2-1.7 mm 1
• LGE pericardial thickness ≥3 mm has 86% sensitivity and 80% specificity for predicting reversible constriction 4
• Moderate or severe pericardial LGE intensity present in 93% of reversible constrictive pericarditis versus 33% of persistent cases 4
• Can distinguish myopericarditis from isolated pericarditis 1

Laboratory Markers

• Elevated CRP and ESR predict reversibility of constrictive pericarditis 4
• Baseline CRP 59±52 mg/L in reversible CP versus 12±14 mg/L in persistent CP 4
• ESR 49±25 mm/h in reversible CP versus 15±16 mm/h in persistent CP 4

Management Algorithm

For Newly Diagnosed Thickened Pericardium with Constrictive Physiology

Step 1: Assess for Reversibility

• Obtain CMR with LGE and measure pericardial thickness 4
• Check inflammatory markers (CRP, ESR) 4
• Look for signs of chronic disease: cachexia, atrial fibrillation, hepatic dysfunction, pericardial calcification 1

Step 2: Trial of Conservative Management (if appropriate)

• Consider empiric anti-inflammatory therapy for 2-3 months in hemodynamically stable patients without chronic disease features 1, 6
• Particularly if pericardial contrast enhancement on CT/CMR and elevated CRP present 1, 6
• This is a Class IIb recommendation from ESC 6

Step 3: Definitive Treatment Decision

• Pericardiectomy is definitive treatment for chronic permanent constrictive pericarditis in symptomatic patients (NYHA class III-IV) 6
• Complete pericardiectomy via midline sternotomy removing both parietal and visceral pericardium is preferred approach 6
• Operative mortality 6-12% 6
• Medical therapy with loop diuretics only when surgery contraindicated or high-risk 6

For Tuberculous Etiology

• Rifampicin-based antituberculosis therapy for 6 months reduces progression to constriction from >80% to <10% 6
• Adjunctive prednisolone for 6 weeks reduces constrictive pericarditis incidence by 46% 6

Critical Pitfalls to Avoid

Do not exclude constrictive pericarditis based on normal pericardial thickness alone - 18% of surgically-proven cases have thickness <2 mm, though all have focal histopathological abnormalities 2

Do not rush to pericardiectomy in newly diagnosed cases without chronic features - transient constriction occurs in 10-20% and may resolve with anti-inflammatory therapy 1

Do not delay pericardiectomy once chronic constriction is established - earlier diagnosis correlates with better outcomes 3

Recognize that pericardial calcification does not impact survival and should not be the sole determinant of surgical timing 6