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This is a clinician-written, evidence-based summary aligned to the USMLE Step 2 CK Content Outline. It is intended for medical students preparing for USMLE Step 2 CK. Management reflects current ACC/AHA, USPSTF, and APA guidelines. Always cross-reference with UpToDate, institutional protocols, and clinical judgment.
Key points
- Diagnosis requires >=2 of 4: (1) pleuritic chest pain worse lying flat/improved sitting forward, (2) pericardial friction rub, (3) diffuse ST elevation with PR depression on ECG, (4) new/worsening pericardial effusion
- Most cases are idiopathic/viral (>80%) and self-limiting
- Treatment: NSAIDs (ibuprofen 600 mg TID or aspirin 650 mg TID) + colchicine 0.5 mg BID x 3 months (COPE/ICAP trials — reduces recurrence)
- Avoid anticoagulation in acute pericarditis (risk of hemorrhagic effusion/tamponade)
- High-risk features: fever >38C, large effusion, tamponade, failure to respond to NSAIDs within 1 week, immunosuppression
Overview
Acute pericarditis is inflammation of the pericardial sac, the most common pericardial disease encountered clinically. The vast majority of cases (~80-90%) in developed countries are idiopathic or presumed viral (Coxsackie B, echovirus, adenovirus, CMV, HIV). Other causes include post-MI (early pericarditis within 24-72h, or Dressler syndrome at 2-10 weeks), uremia, autoimmune (SLE, RA), neoplastic, tuberculosis (think if subacute + HIV/endemic area), post-cardiac surgery (post-pericardiotomy syndrome), and radiation.
Epidemiology
Accounts for ~5% of non-ischemic chest pain ED visits. More common in men age 20-50. Recurrence occurs in 15-30% without colchicine and ~10-15% with colchicine. TB pericarditis should be considered in endemic areas and immunocompromised patients.
Clinical Features
Symptoms
Sharp, pleuritic chest pain — worse with inspiration, lying flat, and swallowing; improved by sitting up and leaning forward
May radiate to trapezius ridge (phrenic nerve irritation — pathognomonic for pericarditis)
Low-grade fever, malaise (viral prodrome common)
Dyspnea if large effusion developing
Signs
Pericardial friction rub: scratchy, high-pitched sound best heard at LLSB with patient sitting forward in end-expiration. Classically has 3 components (atrial systole, ventricular systole, early diastole) but may have only 1 or 2. Evanescent — may come and go
Tachycardia, low-grade fever
Distant/muffled heart sounds if large effusion
Beck triad (hypotension, JVD, muffled heart sounds) = tamponade
Investigations
First-line
ECGStage 1 (acute): diffuse concave-up ST elevation + diffuse PR depression (most specific finding) + PR elevation in aVR. Distinguishes from STEMI: diffuse (not territorial), concave-up (not convex), PR depression, no reciprocal changes, no Q waves. Stage 2: ST normalizes, T flattens. Stage 3: diffuse T inversions. Stage 4: normalization
TroponinMild elevation in up to 30% (myopericarditis) — does not change management if clinical picture fits pericarditis
EchocardiogramAssess for pericardial effusion (may be absent in acute pericarditis), tamponade physiology, wall motion (if myopericarditis)
Basic labsCBC, BMP, CRP/ESR (elevated — also used to monitor treatment response and guide colchicine duration)
Second-line
Chest X-rayUsually normal. Enlarged cardiac silhouette ("water bottle" shape) if effusion >250 mL
Additional workup (if high-risk features)ANA, RF (autoimmune), TSH, BUN/Cr (uremia), HIV, quantiferon/PPD (TB), blood cultures (bacterial), tumor markers/CT (neoplastic). Most routine cases do NOT need extensive workup
Specialist
Cardiac MRIDemonstrates pericardial inflammation (late gadolinium enhancement), pericardial thickening, and myocardial involvement (myopericarditis)
PericardiocentesisDiagnostic + therapeutic if large effusion with hemodynamic compromise. Send fluid for: cell count, protein, LDH, glucose, gram stain, culture, cytology, ADA (TB)
1
First-line (idiopathic/viral)
- NSAIDs: ibuprofen 600 mg TID or aspirin 650 mg TID (aspirin preferred post-MI) x 1-2 weeks then taper
- Colchicine 0.5 mg BID (0.5 mg daily if <70 kg) x 3 months — REDUCES recurrence by ~50% (COPE, ICAP trials)
- Activity restriction: avoid strenuous exercise until symptoms resolve AND CRP normalizes (risk of recurrence/myocarditis worsening)
- PPI for GI protection with NSAIDs
2
Refractory/recurrent
- Low-dose corticosteroids (prednisone 0.25-0.5 mg/kg/day) ONLY if NSAIDs + colchicine fail — steroids increase recurrence risk
- Slow steroid taper over months while maintaining colchicine
- IVIG, azathioprine, or anakinra (IL-1 receptor antagonist) for corticosteroid-dependent recurrent pericarditis (AIRTRIP trial)
- Pericardiectomy: last resort for constrictive pericarditis or intractable recurrence
3
Specific etiologies
- Post-MI (Dressler): aspirin (NOT other NSAIDs — avoid in acute MI) + colchicine
- Uremic: intensify dialysis; NSAIDs often ineffective
- Bacterial/purulent: IV antibiotics + urgent surgical pericardial drainage
- TB: 4-drug anti-TB therapy x 6 months; consider steroids to prevent constrictive pericarditis
- Neoplastic: treat underlying malignancy; pericardiocentesis for tamponade
Complications
- Cardiac tamponade: Large or rapidly accumulating effusion compromises diastolic filling — pericardiocentesis needed
- Recurrent pericarditis: 15-30% without colchicine; colchicine reduces this to ~10-15%
- Constrictive pericarditis: Chronic inflammation leads to fibrotic, thickened, non-compliant pericardium — presents like right HF with JVD, edema, ascites, Kussmaul sign
- Myopericarditis: Concurrent myocardial involvement — mild troponin rise, may have regional wall motion abnormality. Usually benign if LVEF preserved
USMLE Step 2 CK Exam Tips
- 1Diffuse ST elevation + PR depression + pleuritic pain improved sitting forward = pericarditis. PR depression is the most SPECIFIC ECG finding
- 2Distinguish from STEMI: pericarditis has diffuse (not territorial) concave-up ST elevation, PR depression, no reciprocal changes, no Q waves
- 3Trapezius ridge radiation is essentially pathognomonic for pericarditis (phrenic nerve)
- 4Colchicine with NSAIDs from day 1 — this is the evidence-based standard, reduces recurrence by 50%
- 5AVOID anticoagulation in acute pericarditis — risk of hemorrhagic pericardial effusion and tamponade
- 6Post-MI pericarditis: use aspirin (not ibuprofen/naproxen, which may impair myocardial healing)
- 7Steroids INCREASE recurrence risk — only use if NSAID + colchicine fails
- 8Uremic pericarditis: dialysis is the treatment, not NSAIDs
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