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I have comprehensive information from Braunwald's and Rosen's. Now I'll compile a thorough answer.

Pericarditis

Definition and Overview

Pericarditis is inflammation of the pericardium - the two-layered fibroserous sac surrounding the heart. It is a common cause of chest pain, accounting for approximately 5% of all non-ischemic chest pain presentations in the emergency department, with an incidence of ~27.7 cases per 100,000 population/year. Men aged 16-65 are at higher risk than women (RR ~2.0).

Etiology

In developed countries, 80-90% of cases are idiopathic (presumed viral - testing for specific viruses has low yield and little impact on management).
CategoryExamples
Viral (most common)Coxsackievirus, echovirus, adenovirus, EBV, CMV, HIV, influenza
BacterialStaphylococcus, Streptococcus, TB (most common cause in developing countries)
Fungal/parasiticHistoplasma, Candida, Toxoplasma
Post-cardiac injuryPost-MI (early), Dressler syndrome (2-8 wks post-MI), post-cardiac surgery, trauma
Systemic/autoimmuneSLE (40-80% at autopsy), RA, SSc, sarcoidosis, amyloidosis
UremiaMost common systemic disorder associated - treat with intensive dialysis
MalignancyMetastatic (lung, breast, lymphoma); often bloody effusion
RadiationMediastinal irradiation
DrugsHydralazine, procainamide, isoniazid, phenytoin
TB is the most common cause in endemic/developing regions and must always be considered in those populations.

Pathophysiology

The pericardium consists of two layers with a narrow space containing 15-35 mL of fluid normally. Inflammation causes:
  • Edema and thickening of the parietal layer
  • Production of exudative pericardial fluid
  • Increased friction between layers (causing the rub)
Morphological patterns (from Robbins Pathology):
  • Fibrinous/fibrinopurulent - viral/uremic (shaggy, "bread-and-butter" appearance)
  • Suppurative/purulent - bacterial (pus formation)
  • Caseous - tuberculous
  • Hemorrhagic - malignancy
Acute suppurative pericarditis caused by extension from pneumonia
Gross pathology: Acute suppurative pericarditis - note the shaggy, exudative pericardial surface (Robbins Pathology)

Clinical Presentation

Symptoms

  • Chest pain - sharp, pleuritic, retrosternal; worsened by lying supine, deep inspiration, and swallowing; relieved by sitting forward
  • Radiation to the trapezius ridge or back (characteristic - from phrenic nerve involvement)
  • Low-grade fever and myalgias
  • Dyspnea

Signs

  • Pericardial friction rub - pathognomonic, present in ~1/3 of cases
    • Best heard: lower left sternal border, patient leaning forward in full expiration
    • Classic rub = 3 components (ventricular systole + early diastole + atrial contraction), described as "walking on crunchy snow"
    • Evanescent and intermittent - may require repeated auscultation
  • Low-grade fever (<38°C), sinus tachycardia
  • Atrial fibrillation/flutter in ~5%

Diagnostic Criteria

Diagnosis requires at least 2 of the 4 classic criteria:
  1. Characteristic chest pain (positional/pleuritic)
  2. Pericardial friction rub
  3. ECG changes
  4. New or worsening pericardial effusion

ECG Changes (4 classic stages)

StageFindings
I (acute)Diffuse, concave ("saddle-shaped") ST elevation in most leads; PR depression (most specific)
IIST returns to baseline; T waves flatten
IIIT-wave inversions (diffuse)
IVECG normalizes
Key ECG distinction from STEMI: pericarditis has diffuse ST elevation (not focal/territorial) with PR depression, and ST elevation is concave (saddle-shaped), not convex.

Laboratory Testing

  • CRP/ESR/WBC - elevated; CRP is the best marker for activity and guides treatment duration
  • Troponin - mildly elevated in ~30% (myopericarditis); significant elevation suggests concurrent myocarditis
  • BUN/Cr - check for uremia
  • ANA, rheumatoid factor if autoimmune etiology suspected
  • Blood cultures, PPD/IGRA if infectious etiology suspected

Imaging

  • Chest X-ray - often normal in uncomplicated pericarditis; "water-bottle" cardiac silhouette if large effusion (>250 mL)
  • Echocardiography - should be performed in all cases; detects effusion, wall motion abnormalities (myocarditis), tamponade physiology
  • Cardiac MRI - gold standard for detecting pericardial inflammation (gadolinium enhancement); defines extent of involvement and differentiates pericarditis from myocarditis

High-Risk Features (Hospitalize)

The following "red flags" warrant hospitalization and workup for specific etiology:
  • Fever >38°C
  • Subacute onset
  • Large pericardial effusion or cardiac tamponade
  • Failure to respond to NSAIDs after 1 week
  • Myocarditis (elevated troponin)
  • Immunocompromised state
  • Trauma
  • Oral anticoagulant use
  • Pregnancy

Treatment

Acute/Idiopathic Pericarditis

First-line (dual therapy):
DrugDoseDuration
Aspirin750-1000 mg every 8 hr1-2 weeks, then taper over 2-3 weeks
Ibuprofen600-800 mg every 8 hr1-2 weeks, then taper over 2-3 weeks
Colchicine0.5 mg once daily (<70 kg) or 0.5 mg twice daily (≥70 kg)3 months
  • NSAID + colchicine is the recommended combination - colchicine significantly reduces recurrence
  • Taper only when asymptomatic AND CRP normalized
  • Gastric protection (PPI) with NSAIDs
Corticosteroids - use is minimized because they may:
  • Impair clearance of infectious agents
  • Increase risk of recurrence
  • Reserved for: NSAID/colchicine failure or contraindications, autoimmune disease, renal failure, pregnancy
  • If used: low dose prednisone 0.2-0.5 mg/kg/day, taper over 6-12 weeks guided by symptoms and CRP; concurrent colchicine recommended

Specific Causes

  • Uremic pericarditis: intensive dialysis + NSAIDs (indomethacin 25 mg TID); steroids for refractory cases
  • Post-MI (early): aspirin (preferred; avoid ibuprofen which affects infarct healing)
  • Dressler syndrome: NSAIDs (ibuprofen 600 mg QID or indomethacin 25 mg TID); discontinue anticoagulants if possible
  • Tuberculous pericarditis: antituberculous therapy + corticosteroids to reduce constrictive pericarditis risk
  • Bacterial/purulent: IV antibiotics + urgent pericardial drainage
  • Activity restriction: until asymptomatic + CRP normal (athletes: minimum 3 months)

Recurrent Pericarditis

  • Occurs in 15-30% of idiopathic cases
  • Definition: new episode after a symptom-free interval of ≥4-6 weeks with objective evidence of recurrence (rub, ECG changes, new effusion, elevated CRP)
  • Treatment: repeat NSAID + colchicine (same doses)
  • Refractory recurrences: corticosteroids ("triple therapy"); anakinra (IL-1 blocker) shown effective in corticosteroid-dependent recurrent pericarditis
  • Recurrences have not been associated with evolution to constrictive pericarditis in idiopathic cases

Complications

ComplicationNotes
Pericardial effusionCommon (small effusions in most cases)
Cardiac tamponade~3% over 31 months; more common with identified specific cause (bacterial, malignant, TB)
Constrictive pericarditis~1.5-1.8%; extremely rare in idiopathic pericarditis (0.48%)

Cardiac Tamponade (emergency)

  • Beck's triad: hypotension + elevated JVP + muffled heart sounds
  • Pulsus paradoxus >10 mmHg
  • ECG: electrical alternans
  • Treatment: urgent pericardiocentesis

Constrictive Pericarditis

  • Dense fibrous scarring obliterates pericardial space
  • Right-sided venous distension + low cardiac output (similar to restrictive cardiomyopathy)
  • Kussmaul sign (JVP rises on inspiration)
  • Treatment: pericardiectomy

Special Situations

Myopericarditis

  • Up to 15% of pericarditis cases have concurrent myocarditis
  • Elevated troponin, wall motion abnormalities on echo
  • Cardiac MRI confirms myocardial involvement
  • Strict activity restriction; avoid competitive sports for at least 3-6 months

Pericarditis in Autoimmune Disease

  • SLE: typically complicates disease flare; polyserositis; clinically significant tamponade in only 1-2%
  • RA: clinically significant pericarditis in only 1-2%; constrictive pericarditis can develop over months; aggressive DMARD/biologic therapy appears to reduce incidence
  • SSc: small pericardial effusions common, rarely hemodynamically significant; large rapidly accumulating effusions occasionally occur with dSSc
Sources: Braunwald's Heart Disease (11e), Rosen's Emergency Medicine (10e), Robbins & Kumar Basic Pathology (10e), Goldman-Cecil Medicine
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