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Myocarditis: Difference between revisions
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As the cardiac conduction system is in the myocardium, myocarditis predisposes to arrhythmias. It also affects the myocardium’s ability to contract. It may mimic <abbr>[[Acute coronary syndrome|ACS]]</abbr>. | As the cardiac conduction system is in the myocardium, myocarditis predisposes to arrhythmias. It also affects the myocardium’s ability to contract. It may mimic <abbr>[[Acute coronary syndrome|ACS]]</abbr>. | ||
Myocarditis is mostly a disorder of younger adults. | Myocarditis is mostly a disorder of younger adults. It may occur together with [[pericarditis]] as part of "perimyocarditis" or "myopericarditis". Myocarditis is usually self-limiting and patients usually achieve complete remission, but some may develop chronic [[heart failure]]. | ||
== Etiology == | == Etiology == | ||
* Viral ([[Coxsackie | * Viral (most common) | ||
** [[Coxsackie]] group B | |||
** [[Adenovirus|Adenoviruses]] | |||
** [[Enterovirus|Enteroviruses]] | |||
* Bacterial ([[rheumatic fever]]) | * Bacterial ([[rheumatic fever]]) | ||
* Autoimmune disorders | * Protozoa ([[Chagas disease]], due to Trypanosoma cruzi, which is endemic in Latin America) | ||
* Autoimmune disorders (including Giant cell myocarditis) | |||
* [[COVID-19]] | * [[COVID-19]] | ||
* COVID-19 vaccines (rare) | * COVID-19 vaccines (rare) | ||
* [[Immune checkpoint inhibitor|Immune checkpoint inhibitors]] | |||
Determining the exact etiology is rarely possible in clinical practice but it's assumed that most cases are viral. | |||
== Pathology == | |||
The first phase of the disease involves virus-mediated cellular injury. If the immune response is strong enough, the virus will be eliminated but there will be significant myocardial injury as a complications. This is the cause of fulminant myocarditis. | |||
If the immune response is milder, there won't be significant myocardial injury initially, but the virus also won't be eliminated. This causes a more subacute or chronic course, with low-grade myocardial injury over many weeks. | |||
The latter course may progress to a second phase, where progressive myocardial injury, and the myocardial remodellation that follows, causes dilated cardiomyopathy. | |||
== Clinical features == | == Clinical features == | ||
Many are asymptomatic, and symptoms are highly variable. Some have preceding symptoms of viral infection. | Many are asymptomatic, and symptoms are highly variable. Some have preceding symptoms of viral infection (myalgia, fever, upper respiratory symptoms). The cardiac symptoms may range from asymptomatic to: | ||
* New onset or worsening [[heart failure]] | * New onset or worsening [[heart failure]] or even [[cardiogenic shock]] | ||
* [[Acute coronary syndrome]]-like symptoms (chest pain, dyspnoea) | * [[Acute coronary syndrome]]-like symptoms (chest pain, dyspnoea) | ||
* Arrhythmias | * Arrhythmias, both [[Supraventricular arrhythmias|supraventricular]] and [[Ventricular arrhythmia|ventricular]] | ||
Cardiac symptoms may progress slowly or rapidly. | |||
== Diagnosis and evaluation == | == Diagnosis and evaluation == | ||
[[Troponin|Troponins]] are elevated, as are inflammatory markers. [[Electrocardiography|ECG]] is often abnormal, but no findings are specific for myocarditis. ST-elevations and heart blocks are probably the most common. [[Echocardiography]] is important to determine the myocardial contractility and to exclude differential diagnoses. | [[Troponin|Troponins]] and [[NT-proBNP]] are elevated, as are inflammatory markers. [[Electrocardiography|ECG]] is often abnormal, but no findings are specific for myocarditis. ST-elevations and heart blocks are probably the most common. [[Echocardiography]] is important to determine the myocardial contractility and to exclude differential diagnoses like myocardial infarction. There may be regional hypokinesia (like in myocardial infarction) but these regions often do not correspond with the area which is supplied by a single coronary artery (which is the case for myocardial infarction). | ||
[[Magnetic resonance imaging|MRI]] with gadolinium contrast is usually sufficient to diagnose myocarditis and can show oedema and necrosis of the myocardium. Unlike in myocardial infarction, the necrosis is usually localised epicardially rather than subendocardially. In doubtful cases, endomyocardial biopsy (which is the gold standard) can be performed, which may also provide information on the etiology, although this is rarely necessary. | |||
There is no role for viral serology, as studies have shown that serology does not correlate with findings on biopsy PCR. | |||
== Treatment == | == Treatment == | ||
Due to the variable course, myocarditis is an indication for hospital admission. | |||
There is no specific treatment, except if there’s a treatable underlying cause. Most cases are self-limiting. Patients should be continuously monitored for arrhythmias by [[telemetry]]. The patient may require [[Antiarrhythmic drug|antiarrhythmics]] or treatment for [[heart failure]]. Unlike in [[pericarditis]], NSAIDs cannot be used as they are not helpful and might even worsen outcomes. | There is no specific treatment, except if there’s a treatable underlying cause. Most cases are self-limiting. Patients should be continuously monitored for arrhythmias by [[telemetry]]. The patient may require [[Antiarrhythmic drug|antiarrhythmics]] or treatment for [[heart failure]]. Unlike in [[pericarditis]], NSAIDs cannot be used as they are not helpful and might even worsen outcomes. | ||
Patients should avoid strenous physical activity for at least 3-6 months after myocarditis to decrease the risk of fatal arrhythmia. | |||
== Complications == | == Complications == | ||