Table Of Contents

Myocarditis

Definition

• Myocardial inflammation often accompanied by cardiac dysfunction.
• Major cause of SCD in adults < 40 years old.

Etiology

• Idiopathic/viral (Coxsackie B, adenovirus, influenza, CMV, EBV, parvovirus).
  • lymphocytic infiltrate with focal necrosis highly indicative of viral myocarditis.
• Parasitic ( Trypanosoma cruzi, Toxoplasma gondii)
• Bacterial ( Borrelia burgdorferi, Mycoplasma pneumoniae, Corynebacterium diphtheriae)
• Toxins ( carbon monoxide, black widow venom)
• Drugs ( doxorubicin, cocaine)
• Autoimmune ( Kawasaki disease, sarcoidosis, SLE, polymyositis/dermatomyositis)
• Giant cell myocarditis

Clinical Features

• Variable presentation from subclinical to symptomatic (chest pain, heart failure, shock).
• Nonspecific ECG changes, TTE with diffuse wall motion abnormalities.

<aside> 💡 Diagnostic Criteria

• Elevated cardiac biomarkers
• ECG changes
• Abnormal cardiac function (on ECHO/MRI).
  • Low suspicion for CAD based on clean cardiac catheterization or age.
  • Cardiac MRI and/or myocardial biopsy for further characterization. </aside>

Complications

• Sudden death
• Arrhythmias, heart block