Myocarditis

Question 1

Define myocarditis

Answer 1

Inflammation of the myocardium - can lead to severe, acute cardiac failure requiring organ support

Question 2

What is the relevant epidemiology of myocarditis?

Answer 2

20 cases per 100,000 person years
Peak incidence 6-15yrs
Less common than pericarditis and ACS

Question 3

What is the most common aetiology of myocarditis?

Answer 3

Enteroviruses especially Coxsackievirus B
Human Herpes virus 6 - identified in up to 60% of biopsied cases
Parovirus B-19 - identified in up to 30% of biopsied cases
Influenza A
HIV

Question 4

Bacterial myocarditis is less common, what bacteria can cause myocarditis?

Answer 4

Rheumatic fever (streptococcus A)
Trypanosoma cruzi (Chagas disease)
Diphtheria - most common cause of myocarditis worldwide

Question 5

What are the different causes of myocarditis?

Answer 5

Viral
Bacterial
Radiation - exacerbated by chemotherapy drugs
Autoimmune - SLE, sarcoidosis, giant cell myocarditis, Kawasaki disease
Drugs - Clozapine, Pembrolizumab

Question 6

What is the underlying pathophysiology of myocarditis?

Answer 6

1. Direct cellular injury resulting from viral infection
   2.Immune response arising from the viral proteins intracellularly.
2. Autoantibodies may be implicated in the inflammation secondary to autoimmune disease and may be triggered by a viral infections - TNFalpha, autoreactive T cells and IL-10

Question 7

What are the key clinical features of myocarditis?

Answer 7

Asymptomatic
Chest pain
Systemic upset - fatigue, fever, lethargy
SOB
Reduced exercise tolerance
Palpitations
Tachycardia
Collapse - cardiac syncope
Sudden death (8.6% of sudden deaths)
Recent history of preceding viral URTI or gastro.

Question 8

On examination what are the findings of myocarditis?

Answer 8

Heart Failure - fluid overload, raised JVP, pulmonary oedema, peripheral oedema
Pericardial frication rub - if concurernt pericarditis
Pansysytolic murmur - mitral regurg

Question 9

What might an ECG of a patient with myocarditis show?

Answer 9

ST elevation/depression
T wave inversion
Atrial arrhythmias
Transient AV block

Question 10

What investigations should be done for a patient with suspected myocarditis?

Answer 10

Bedside: ECG, resp viral screening, urine dip for blood and protein.
Bloods: FBC, ESR, CRP, Cardiac enzymes (creatine kinase and troponin)
Anti-nuclear antibodies, RF, Serum ACE, Ds-DNA,
Viral screening
Imaging: echo, cardiac MRI, cardiac biopsy for definitive diagnosis

Question 11

What are the key principles of management in myocarditis?

Answer 11

Supportive:
oxygen where required
Monitoring and controlling any underlying arrhythmias
Fluid balance management
Easy escalation to specialist intensive care physician - early review with cardiac ICU as can deteriorate quickly.
Organ support as required.
If suspect Giant Cell Myocarditis then give steroids.

Question 12

What treatment should be given to patients recovering from myocarditis?

Answer 12

Avoid strenuous exercise
Heart Failure management - ACEi, beta blockers and aldosterone antagonists to treat symptoms of heart failure.
Serial echos to assess recovery

Question 13

What are some short term complications of myocarditis?

Answer 13

Due to damage to cardia cmuscel
Cardiogenic shock - insuffienct cardiac output and organ hypoperfusion
Cardiac arrhythmias
Sudden death

Question 14

What are some long-term complications of myocarditis?

Answer 14

Dilated cardiomyopathy - 20%
Heart failure - requiring medical management.

Question 15

What is the prognosis of myocarditis?

Answer 15

50% of patients make a full recovery within 4 weeks.

Question 16

What are some risk factors for myocarditis?

Answer 16

Infection - mainly viral, worldwide most common is Trypanosoma cruzi (Chagas disease)
HIV infection
Autoimmune disease - SLE, scleroderma and sarcoidosis
Peripartum and postnatal periods