Myocarditis

This page is for adult patients. For pediatric patients, see: myocarditis (peds)

Background

Inflammatory (dilated) cardiomyopathy caused by necrosis of myocytes

Causes

Infectious agents
- Enterovirus (Coxsackie B) and adenovirus most common
- Influenza A and B
- Hepatitis B
- Beta-hemolytic streptococcus
- Mycoplasma
- Mumps
- CMV
- Toxoplasma
- Chagas (most common cause worldwide
- Trichinosis
- Diphtheria
- Lyme disease
Drugs
- Doxorubicin
- Cocaine

Phases

Acute
- Viral cytotoxicity and focal necrosis
Subacute
- Host's humoral/immune response leading to further cell injury
Chronic
- Diffuse myocardial fibrosis and cardiac dysfunction

Clinical Features

Typically young patients (20 - 50 years) with few risk factors for CAD
Chest pain
Pericardial friction rub
Flu-like symptoms
- [[Fever], fatigue, myalgia, nausea and vomiting
- Tachycardia (out of proportion to fever)
- Tachypnea
New onset congestive heart failure
Pediatric patients:
- Grunting
- Retractions
- Ronchi
Infants may have fulminant syndrome
- Fever
- Cyanosis
- Respiratory distress
- Tachycardia
- Heart failure
- Ventricular dysrhythmias

Consider this diagnosis in the septic-appearing patient who gets WORSE after receiving IV fluids

Differential Diagnosis

Consider other causes of CHF

Chest pain

Critical

Acute Coronary Syndromes
Aortic dissection
Cardiac tamponade
Pulmonary embolism
Tension pneumothorax
Esophageal perforation (Boerhhaave's syndrome)
Coronary artery dissection

Emergent

Nonemergent

Stable angina
Asthma exacerbation
Valvular Heart Disease
Aortic Stenosis
Mitral valve prolapse
Hypertrophic cardiomyopathy
Pneumonia
Pleuritis
Tumor
Pneumomediastinum
Esophageal Spasm
Gastroesophageal Reflux Disease (GERD)
Peptic Ulcer Disease
Biliary Colic
Muscle sprain
Rib Fracture
Arthritis
Costochondritis
Spinal Root Compression
Thoracic outlet syndrome
Herpes Zoster / Postherpetic Neuralgia
Psychologic / Somatic Chest Pain
Hyperventilation
Panic attack

Evaluation

ECG
- Sinus tachycardia
- Low voltages
- Prolonged QTc
- AV block
- ST elevations (Usually >1 vessel distribution)
Elevated troponin
Echocardiography
- Decreased LVEF
- Global hypokinesis
- Regional wall motion abnormalities
Contrast MR
Nuclear Study
- Widespread uptake indicating myocyte necrosis
Viral titres
Endocardial biopsy: Gold standard, but rarely used

Management

Acute phase
- Antiviral agents (Pleconaril/Ribavirin) may be effective
Subacute phase
- Studies have not shown efficacy of immunosupressants
- Pediatric patients may receive high-dose IVIG
Chronic phase
- Treatment for CHF symptoms
- Ventricular Assist Devices (VAD)
- Cardiac transplant

Disposition

If CHF is present, admit to monitored bed
If hemodynamically unstable, admit to ICU

Prognosis

Fulminant myocarditis has best prognosis
Mortality: 20% 1 yr/ 50% 5 yr
Children with 70% survival rate at 5 yrs

Complications

See Also

References

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