myocarditis
Table of Contents
myocarditis
see also:
Introduction
- myocarditis should be especially considered in the differential of chest pain, arrythmias, exercise intolerance or syncope in adolescents and young adults
- can be mistaken for asthma in children
- more prevalent in young people, with a median age between 20 and 40 years and affects males more than females with 75-84% of acute cases being male
- in the elderly it is more commonly associated with medications such as ICIs and clozapine
- the inflammatory myo-pericarditis syndrome (IMPS) is a newly introduced umbrella term encompassing the full spectrum of inflammatory myocardial (myocarditis) and pericardial (pericarditis) diseases, including those overlapping both conditions.
Aetiology
- viral
- Coxsackie virus
- Parvovirus B19
- HIV / AIDS - particularly common in the late stages of HIV infection
- bacterial, protozoal or fungal infections (usually only in the immunocompromised)
- H. influenzae
- toxic shock syndrome
- various parasites
- NB. the most common cause worldwide is Chagas disease, which is endemic to Central and South America that results from infection with the protozoan Trypanosoma cruzi
- immune conditions:
- following certain mRNA vaccines
- appears to be due to induced production of CXCL10 by macrophages which in turn causes T cells to produce increased levels of IFN-gamma resulting in increased local neutrophil activity and inflammation 1)
- this appears to be blocked by genistein, a mild estrogen-like substance derived from soybeans which has anti-inflammatory activity and the ability to counter marijuana-induced damage to blood vessels and heart tissue
- medications
- chemotherapy for cancers especially immune checkpoint inhibitors (ICI)
- drugs and toxins
- heavy metals - copper, iron poisoning
- as part of pericarditis
- giant cell myocarditis
- rare causes:
- Idiopathic Hypereosinophilic Syndrome-Related Myocarditis
- usually associated with either:
- toxic reaction to a drug eg. DRESS syndrome
- the consequence of certain types of parasite and protozoan infections
- the result of excessively high levels of activated blood eosinophils due to a wide range of other causes including eosinophilic leukaemia,
- see eosinophilia
- Isolated Right Ventricular Lymphocytic Myocarditis
- during the acute stage of myocarditis, patients are advised to rest completely, since exercise has been associated with arrhythmias and sudden cardiac death
- patients Rx with immune checkpoint inhibitors (ICI) who develop suspected myocarditis - immediately cease ICI and start high dose steroids
- diagnostic triage within 24hrs is advised for these patients to stop the inflammatory process and stabilise the patient
- patients with sarcoid myocarditis should be considered for implantable cardiac defibrillator (ICD) to prevent sudden cardiac death if:
- sustained VT / VF or aborted cardiac arrest, or,
- LVEF < 35%
- combined immunosuppressive Rx is generally recommended for those with giant cell myocarditis (GCM)
- endomyocardial biopsy should be considered for suspected GCM if unexplained new onset heart failure with normal or dilated LV and new ventricular arrhythmias, 2nd or 3rd degree HB, or failure to respond to usual care within 1-2wks
- all patients should have follow up within 6 months including Holter, echo, cardiac MRI
- long term follow up is recommended for those with complicated myocarditis to identify a potential progression and new complications
Clinical features
- may present with either:
- ischaemic sounding chest pain but may be sharp or stabbing and may radiate through to the back or to arm(s)
- features of pericarditis
- palpitations
- exercise intolerance or features of heart failure
- syncope
- sudden death
- ECG may show dynamic changes, arrhythmias or heart blocks (none of which pathognomonic, and approx. half are normal)
- most commonly, there is a sinus tachycardia with non-specific ST or T wave changes
- new T wave inversion develops within 48hrs in ~half of patients 2)
- if pericarditis is also present (ie. myopericarditis) then ECG changes of this may also be present
- presence of Q waves, a widened QRS complex, prolongation of the QT interval, high degree AV nodal blockade, and ventricular tachyarrhythmias are associated with a poor prognosis when seen on ECG in people with myocarditis, while ST elevation with a typical early repolarization pattern is associated with a better prognosis. 3)
- serial troponin rise
DDx
- is it something other than myocarditis? see the adult patient with chest pain in the ED
- if it is myocarditis, what is the cause - see above under aetiology
Mx in ED
- usual bloods including FBE, U&E, Ca, Mg, PO4, LFTs, CRP and serial troponins (plus consider HCG, D-Dimer and TSH if appropriate)
- cardiac monitor
- CXR
- Rx arrhythmias or heart blocks as per usual
- consult with cardiology
- consider viral serology - HIV / AIDS, hepatitis C virus (lyme disease if appropriate)
- echocardiography
- Rx the cause where possible
- consider cardiac MRI
- consider endomyocardial biopsy
- high risk myocarditis
- haemodynamic instability
- intermediate risk myocarditis not responding to conventional Rx to detect a specific histologic subtype and presence of viral genome
myocarditis.txt · Last modified: 2025/12/10 20:25 by gary1