Myocarditis

Question 1

What is myocarditis?

Answer 1

Acute inflammation + necrosis of cardiac muscle (myocardium) in the absence of acute/ chronic ischaemia

Question 2

Describe the epidemiology of myocarditis

Answer 2

Incidence difficult to measure accurately
Coxsackie B virus is most common in Europe + USA
Chagas disease is most common in South America

Question 3

Describe the aetiology of myocarditis

Answer 3

Usually IDIOPATHIC (50%)
Infectious
Non-infectious

Question 4

List 4 types of infectious causes of myocarditis with examples

Answer 4

Viruses: Coxsackie B, Echovirus, EBV, CMV, Adenovirus, Influenza A + B
Bacteria: Post-strep, TB, Diptheria, Lyme disease
Fungal: Candidiasis, Aspergillus
Protozoal: Trypanosomiasis (Chagas disease), Helminths (Trichinella)

Question 5

List non-infectious causes of myocarditis

Answer 5

Systemic: SLE, sarcoidosis, polymyositis
Vasculitis: Kawasaki disease
Hypersensitivity myocarditis: sulphonamides
Drugs: Chemotherapy agents (e.g. doxorubicin, streptomycin)
Other: Cocaine, heavy metals, radiation, toxins

Question 6

List 8 symptoms of myocarditis

Answer 6

Prodromal flu-like illness with:
Fever
Malaise
Fatigue
Lethargy
Breathlessness (due to pericardial effusion/ myocardial dysfunction)
Orthopnea if manifests as congestive HF
Palpitations
Sharp chest pain (suggesting also pericarditis; positional)

Question 7

List 5 signs of myocarditis

Answer 7

Tachycardia
Soft S1
Signs of complications (e.g. HF, arrhythmia) e.g. rales, elevated JVP, S4 gallop, hypotension, AMS
If myopericarditis present => pericardial friction rub
Lymphadenopathy in sarcoidosis-associated myocarditis

Question 8

What bloods are taken in myocarditis?

Answer 8

FBC: raised WCC if infective cause
U&E
ESR/ CRP raised
Cardiac enzymes: may be raised; in clinical setting, +ve troponin I or T confirms dx
Serum CK elevated
Serum Ck-MB mildly elevated
Serum troponin elevated
Negative antimyosin scintigraphy excludes acute myocarditis
Tests to identify cause (e.g. viral/bacterial serology, ANA, TFT)

Question 9

What may be seen on ECG in myocarditis?

Answer 9

Non-specific T wave + ST changes
Atrial arrhythmias
Transient AV block

Question 10

Describe CXR in myocarditis

Answer 10

May be NORMAL

May show cardiomegaly (Congestive HF)

Question 11

What may be seen on echocardiogram in myocarditis?

Answer 11

Global/ regional LV motion abnormalities + dilation

Question 12

What investigations may be considered in myocarditis?

Answer 12

Myocardial Biopsy (Rarely): shows histopath findings of myocardial cellular infiltrates
Coronary angiography: to exclude MI
Cardiac MRI: to distinguish between ACS + myocarditis