Myocarditis

Question 1

What is the definition of myocarditis?

Answer 1

Acute inflammation and necrosis of cardiac muscle (myocardium)

Question 2

What is the epidemiology of myocarditis?

Answer 2

Incidence is difficult to measure accurately

Coxsackie B virus is most common in Europe and USA

Chagas disease is most common in South America

Question 3

What is the aetiology of myocarditis?

Answer 3

Usually IDIOPATHIC

Viruses - Coxsackie B, EBV, CMV, Adenovirus and Influenza

Bacteria - Post-streptococcal, Tuberculosis and Diphtheria

Fungal - Candidiasis

Protozoal - Trypanosomiasis (Chagas disease)

Helminths - Trichinosis

Non-infective

• Systemic: SLE, sarcoidosis, polymyositis
• Hypersensitivity myocarditis: sulphonamides

Drugs - Chemotherapy agents (e.g. doxorubicin, streptomycin)

Others - Cocaine, heavy metals, radiation

Question 4

What are the presenting symptoms of myocarditis?

Answer 4

Prodromal flu-like illness with:

• Fever
• Malaise
• Fatigue
• Lethargy

Breathlessness (due to pericardial effusion/myocardial dysfunction)

Palpitations

Sharp chest pain (suggesting there is also pericarditis)

Question 5

What are the signs of myocarditis upon physical examination?

Answer 5

Signs of pericarditis

Signs of complications (e.g. heart failure, arrhythmia)

Question 6

What are the appropriate investigations for myocarditis?

Answer 6

Bloods

• FBC - raised WCC if infective cause
• U&E
• ESR/CRP - raised
• Cardiac enzymes - may be raised
• Tests to identify cause (e.g. viral/bacterial serology, ANA, TFT)

ECG

• Non-specific T wave and ST changes
• PERICARDITIS: widespread saddle-shaped ST elevation

CXR

• May be NORMAL
• May show cardiomegaly

Pericardial Fluid Drainage

• Measure glucose, protein, cytology, culture and sensitivity
• Helps identify causative organism

Echocardiography

• Assesses systolic/diastolic function
• Wall motion abnormalities
• Pericardial effusions

Myocardial Biopsy
- Rarely required