Myocarditis

Question 1

Define myocarditis

Answer 1

Acute inflammation and necrosis of cardiac muscle (myocardium)

Question 2

Summarise 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

Explain the aetiology/risk factors of myocarditis

Answer 3

Usually IDIOPATHIC

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

Bacteria - Post-streptococcal, Tuberculosis, 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

Recognise 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

Recognise the signs of myocarditis on examination

Answer 5

Signs of pericarditis

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

Question 6

Identify appropriate investigations for myocarditis

Answer 6

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