Myocarditis Flashcards
Define myocarditis.
Inflammation of the myocardium in the absence of the predominant acute or chronic ischaemia as in CAD
Who is most affected by myocarditis?
- Very variable presentation so difficult to estimate true incidence and prevalence
- ?M>F
What are the risk factors for myocarditis?
- Infection e.g. HIV; most common cause of myocarditis worldwide is Trypanosoma cruzi with an estimated 18 million people infected
- Smallpox vaccination
- AI/immune-mediated diseases - SLE, scleroderma etc
- Women in peripartum and postnatal periods
- Drugs and toxins*
*anthracyclines, arsenic, carbon monoxide, ethanol, iron, interleukin-2, cocaine, smallpox vaccination, SARS-CoV-2 vaccination, catecholamines, cyclophosphamide, heavy metals (copper, iron, lead), antibiotics (penicillins, cephalosporins, sulfonamides, amphotericin B), thiazide diuretics, antiepileptics (carbamazepine, phenytoin, phenobarbital), digoxin, lithium, amitriptyline, dobutamine, and snake bites.
What is the aetiology of myocarditis?
Infectious:
- Viral e.g. influenza A and B, adenovirus, coxsackie B virus
- Bacterial e.g. myobacterial, streptococcal, mycoplasma
- Spirochetal e.g. Lyme disease, syphilis, leptospirosis
- Mycotic e.g. aspergillus, candida, histoplasma
- Protozoal e.g. toxoplasmosis, malaria
- Rickettsial e.g. Q fever
Non-infectious:
- Toxins/drug relates - arsenic, ethanol, CO, cocaine, heavy metals
- Hypersensitivity - antibiotics, thiazide diuretics, antiepileptics, lithium, digoxin
- Systemic disorders - sarcoidosis, thyrotoxicosis, IBD
How does myocarditis present?
- Flu-like prodrome - 2-3 weeks before, with fever, malaise, lethargy, fatigue
- Positional chest pain (worse when lying down)
- Dyspnoea/orthopnoea - new onset CHF
- SOB
- Palpitations
- Elevated neck veins
- S3 and S4 gallop
- Pericardial friction rub
- Arrhythmias e.g. sustained VT
- Peripheral hypoperfusion - can present as left ventricular systolic dysfunction
How do you diagnose myocarditis?
Investigations:
- ECG: non-specific ST changes (elevation and depression common), T-wave abnormalities
- CXR - pulmonary infiltrates in the setting of myocarditis-induced CHF
- CK, troponins - mildly elevated - not present in pericarditis.
- BNP - may be elevated if CHF
- TTE echo - may show ventricular motion abnormalities
Other:
- Endomyocardial biopsy (diagnostic but not routinely performed) - done in patients with persistent symptoms who do not respond to treatment
- Coronary angio - exclude MI
- Cardiac MRI
- Viral PCR
What is the most common cause of heart failure worldwide?
Trypanosoma cruzi related myocarditis = Chagas heart disease
What is the management of haemodynamically stable myocarditis?
In ventricular dysfunction:
- ACEi/ARB/valsartan - improve survival in CHF
- Diuretic - improves patient comfort
- Vasodilator or ionotropes - decrease pulmonary and LV filling pressures
- Beta-blockers - start once acute treatment given
- Aldosterone - given in NYHA stage II-IV heart failure
Anticoagulation - prevent LV thrombus formation
+/- corticosteroids - treat underlying autoimmune condition
+/- permanent pacemaker - often required in Chagas’ disease due to conduction abnormalities and ventricular arrhythmias
What is the management of haemodynamically unstable myocarditis?
Some develop fulminant HF or cardiogenic shock and require…
- Pulmonary artery catheter - monitoring cardiac filling and response to therapy
- Vasodilator - sodium nitroprusside
- Vasopressors - noradrenaline
- Positive inotropes - dobutamine
- Intra-aortic balloon pump or LV assist device (LVAD) - bridge to recovery or heart transplant
What are the complications of myocarditis?
- AF
- VTs
- Dilated cardiomyopathy
- Sudden cardiac death
- Multisystem organ failure
What is the prognosis of myocarditis?
- Varies
- Severity of illness at presentation correlates with long-term outcomes
- Myocardial oedema without fibrosis is also associated with a positive prognosis
