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Pericarditis and Myocarditis for USMLE Step 2 & COMLEX-USA Level 2

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Pericarditis
  • Etiology:
    • Infectious: Viral (Coxsackievirus, influenza), bacterial (tuberculosis), fungal.
    • Non-infectious:
    • Post-myocardial infarction (acute pericarditis, Dressler syndrome).
    • Autoimmune diseases (systemic lupus erythematosus, rheumatoid arthritis).
    • Uremia, malignancy, trauma, radiation exposure.
  • Clinical Presentation:
    • Chest pain: Sharp and pleuritic, improves with sitting forward.
    • Pericardial friction rub: Scratchy sound along the left sternal border.
    • Fever and dyspnea with large pericardial effusion.
  • Diagnosis:
    • ECG findings:
    • Diffuse ST-segment elevation with PR-segment depression (early).
    • Later normalization followed by T-wave inversion.
    • Echocardiography: Identifies effusions and signs of tamponade.
    • Laboratory findings: Elevated ESR and CRP.
  • Complications:
    • Cardiac tamponade: Beck’s triad (hypotension, distant heart sounds, jugular venous distension).
    • Constrictive pericarditis: Chronic fibrosis causing diastolic dysfunction.
  • Treatment:
    • NSAIDs and colchicine: First-line treatment.
    • Glucocorticoids: For refractory or autoimmune cases.
    • Pericardiocentesis: For tamponade or large effusions.
    • Antibiotics: If bacterial etiology is confirmed.
    • --
Myocarditis
  • Etiology:
    • Infectious: Viral (Coxsackievirus, adenovirus, parvovirus B19), bacterial (Lyme disease), parasitic (Chagas disease).
    • Non-infectious:
    • Autoimmune (sarcoidosis, systemic lupus erythematosus).
    • Drug toxicity (chemotherapeutics, immune checkpoint inhibitors).
  • Clinical Presentation:
    • Chest pain: May mimic acute coronary syndrome.
    • Heart failure symptoms: Dyspnea, orthopnea, and lower extremity edema.
    • Arrhythmias: Palpitations, syncope, or sudden cardiac death.
    • Systemic signs: Fever, fatigue, and myalgias in viral cases.
  • Diagnosis:
    • ECG: ST/T wave abnormalities, heart block, or ventricular arrhythmias.
    • Echocardiography: Shows reduced ejection fraction and wall motion abnormalities.
    • Cardiac MRI: Detects myocardial inflammation and edema.
    • Endomyocardial biopsy: Gold standard in cases of severe or refractory disease.
    • Labs: Elevated troponin and BNP levels.
  • Complications:
    • Heart failure: Acute decompensation or chronic dysfunction.
    • Arrhythmias: Ventricular tachycardia or fibrillation.
    • Dilated cardiomyopathy: Result of chronic myocardial damage.
    • Sudden cardiac death: Due to ventricular arrhythmias.
  • Treatment:
    • Supportive therapy: Diuretics, ACE inhibitors, beta-blockers for heart failure.
    • Antiarrhythmic medications: For ventricular arrhythmias.
    • Immunosuppression: Used in autoimmune myocarditis (e.g., steroids).
    • Mechanical support: ECMO or ventricular assist devices in severe cases.
    • --
Differences Between Pericarditis and Myocarditis
  • ECG findings:
    • Pericarditis: Diffuse ST-segment elevation, PR-segment depression.
    • Myocarditis: ST/T wave changes, heart block, or arrhythmias.
  • Complications:
    • Pericarditis: Cardiac tamponade, constrictive pericarditis.
    • Myocarditis: Heart failure, arrhythmias, sudden cardiac death.
    • --
Key Points
  • Pericarditis presents with pleuritic chest pain, pericardial rub, and diffuse ST elevation. It is managed with NSAIDs, colchicine, and pericardiocentesis for tamponade.
  • Myocarditis can mimic acute coronary syndrome and lead to heart failure, arrhythmias, or cardiomyopathy. Cardiac MRI and biopsy are diagnostic in severe cases.
  • Pericarditis is associated with tamponade and constrictive pericarditis, while myocarditis carries risks of ventricular arrhythmias and sudden death.