Myocarditis
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
- Infectious agents
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 syndrome
- 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 (ACS)
- Aortic dissection
- Cardiac tamponade
- Coronary artery dissection
- Esophageal perforation (Boerhhaave's syndrome)
- Pulmonary embolism
- Tension pneumothorax
Emergent
- Cholecystitis
- Cocaine-associated chest pain
- Mediastinitis
- Myocardial rupture
- Myocarditis
- Pancreatitis
- Pericarditis
- Pneumothorax
Nonemergent
- Aortic stenosis
- Arthritis
- Asthma exacerbation
- Biliary colic
- Costochondritis
- Esophageal spasm
- Gastroesophageal reflux disease
- Herpes zoster / Postherpetic Neuralgia
- Hypertrophic cardiomyopathy
- Hyperventilation
- Mitral valve prolapse
- Panic attack
- Peptic ulcer disease
- Pleuritis
- Pneumomediastinum
- Pneumonia
- Rib fracture
- Stable angina
- Thoracic outlet syndrome
- Valvular heart disease
- Muscle sprain
- Psychologic / Somatic Chest Pain
- Spinal Root Compression
- Tumor
Evaluation
- ECG
- Sinus tachycardia
- Low voltages
- Prolonged QTc
- AV block
- ST elevations (Usually >1 vessel distribution)
- Elevated troponin
- Echocardiogram
- 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 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
Disposition
- If CHF: Admit to monitored bed; ICU for hemodynamic instability
- Fulminant myocarditis has best prognosis
- Mortality: 20% 1 yr/ 50% 5 yr
- Children with 70% survival rate at 5 yrs
Complications
- Ventricular dysrhythmias
- LV anneurysm
- CHF