Myocarditis

Background

Inflammatory cardiomyopathy (dilated cardiomyopathy) caused by necrosis of myocytes from infectious agents, their toxins, and cytotoxic effects of activated host immunity
Majority caused by enterovirus (Cocksackie B) and adenovirus. Also influenza A/B, Hep B, B Hemolytic Streptococcus, Mycoplasma, Mumps, CMV and Toxoplasma (cardiac transplant), Chagas (leading cause worldwide) Trichinosis, Diphtheria, Lyme
Drugs: Doxorubicin, Cocaine

Typically young/few risk factors for CAD
Chest pain
No sensitive symptom or sign but can have flu like syndrome: fever, fatigue, myalgia, nausea and vomiting; tachycardia (out of proportion to fever), tachypnea, new onset CHF
In Peds: grunting, retractions, ronchi. Infants may have fulminant syndrome: Fever, cyanosis, respiratory distress, tachycardia, cardiac failure, ventricular dysrhythmias
May have pericardial friction rub
Consider this diagnosis in the septic-appearing patient who gets WORSE after receiving IV fluids.

ECG: Sinus tachycardia, low voltages, prolonged QTc, AV block, Acute MI pattern (Usually >1 vessel distribution)
TropI: Elevated
Echo: Decreased LVEF, global hypokinesis, regional wall motion abnormalities
Contrast MR
Nuclear Study: Widespread uptake indicating myocyte necrosis
Viral titers
Endocardial biopsy: Gold standard

Acute Phase: Antiviral agents may be effective with replicating virus: Pleconaril/Ribavirin
Subacute: Studies have not shown efficacy of immunosupressants. Peds: High dose IVIG
Chronic: Treat CHF symptoms, Ventricular Assist Devices (VAD), cardiac transplant