Acute Pericarditis

Cardiology

OverviewWhoPresentationMechanismWorkupManagementPivots

Illness script · Cardiology

Acute Pericarditis

Inflammation of the pericardial sac, most commonly viral, causing sharp chest pain, friction rub, and characteristic ECG changes.

This illness script for Acute Pericarditis covers predisposing factors, classic presentation, mechanism, workup, management, and the clinical pivots that separate it from look-alikes—written for USMLE Step 1 and clerkship reasoning.

Updated Aug 17, 2026All scripts

01

Predisposing factors

  • Most common cause: viral (Coxsackievirus B, echovirus, adenovirus)
  • Young, otherwise healthy males affected most often
  • Bacterial causes: TB (developing world), Staph/Strep (post-surgical)
  • Post-MI: early (1–3 days, fibrinous) or late (weeks, Dressler syndrome)
  • Other causes: uremia, SLE, malignancy, radiation, drugs (hydralazine, procainamide)
  • Recent URI or GI illness preceding chest pain is classic

02

Presentation

  • Sharp, pleuritic chest pain — worse supine, relieved leaning forward (pathognomonic posture)
  • Pain may radiate to trapezius ridge (phrenic nerve irritation — highly specific)
  • Pericardial friction rub: scratchy, high-pitched, best heard at LLSB with patient leaning forward
  • Low-grade fever, malaise, dyspnea common
  • Acute onset; often preceded by viral prodrome (URI/GI symptoms)
  • Beck's triad (hypotension, JVD, muffled heart sounds) suggests tamponade complication

03

Pathophysiology

  • Infectious or immune-mediated inflammation of visceral and parietal pericardial layers
  • Inflammation → fibrinous exudate → pericardial friction rub
  • Fluid accumulation can develop → risk of cardiac tamponade
  • Recurrent inflammation (≥2 episodes) defines recurrent pericarditis

04

Diagnostics

  • ECG: diffuse ST elevation (saddle-shaped, concave up) in most leads + PR depression — key differentiator from MI
  • PR depression most specific ECG finding for pericarditis
  • Stage II ECG: ST normalizes; Stage III: T-wave inversions; Stage IV: ECG normalizes
  • Echo: first-line to rule out pericardial effusion/tamponade
  • Elevated ESR, CRP, WBC support diagnosis; troponin may be mildly elevated if myopericarditis
  • Diagnosis requires ≥2 of 4 criteria: typical pain, friction rub, ECG changes, new effusion

05

Management

  • First-line: NSAIDs (ibuprofen 600 mg TID or aspirin) + colchicine (0.5 mg BID) for 3 months — colchicine reduces recurrence
  • Restrict strenuous activity until symptom-free and CRP normalized
  • Corticosteroids only if NSAID/colchicine contraindicated or refractory (increases recurrence risk — avoid as first-line)
  • Treat underlying cause (dialysis for uremia, antibiotics for bacterial)
  • Hospitalize if: fever >38°C, subacute onset, large effusion, immunosuppressed, trauma, oral anticoagulant use, troponin elevation

06

Clinical pivots

How to separate this script from the look-alikes that show up on exams and on the wards.

  • ST-elevation MI (STEMI)

    Pericarditis has diffuse concave (saddle-shaped) ST elevation + PR depression in multiple leads; STEMI has focal convex ST elevation in a coronary territory with reciprocal changes.

  • Myocarditis

    Myocarditis presents with heart failure symptoms and significantly elevated troponin; pericarditis has minimal troponin rise and preserved LV function.

  • Pulmonary Embolism

    PE causes pleuritic chest pain but typically shows sinus tachycardia ± S1Q3T3 on ECG, not the diffuse ST/PR changes of pericarditis.

  • Aortic Dissection

    Dissection causes tearing/ripping pain radiating to the back with pulse differentials; pericarditis pain is positional and relieved leaning forward.

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Educational use only. This illness script is a study framework, not medical advice. Confirm decisions with current guidelines and your clinical supervisors.