---
title: Myocarditis
description: What myocarditis is, why it develops, how it is recognised, how it is treated and when urgent help is needed.
type: disease
aliases:
  - acute myocarditis
  - fulminant myocarditis
  - inflammation of the heart muscle
sources:
  - tier: guideline
    org: esc
    title: 2025 ESC Guidelines for the management of myocarditis and pericarditis
    year: 2025
    doi: 10.1093/eurheartj/ehaf192
    url: https://doi.org/10.1093/eurheartj/ehaf192
  - tier: guideline
    org: minzdrav-rf
    title: Миокардиты
    year: 2025
    url: https://cr.minzdrav.gov.ru/view-cr/153_2
  - tier: reference
    org: statpearls
    title: Viral Myocarditis
    year: 2023
    url: https://www.ncbi.nlm.nih.gov/books/NBK459259/
sources_checked: 2026-10-12
review: null
---

Myocarditis is an inflammatory disease of the myocardium, the heart muscle.<Cite n={1} /> The inflammation may affect separate areas of the myocardium or spread through it diffusely.<Cite n={3} /> The Russian Ministry of Health guideline calls myocarditis a group term: inflammation of the myocardium can be infectious, toxic (including drug-induced), allergic, autoimmune or of unknown origin.<Cite n={2} /> It shows itself in very different ways: from no symptoms, mild breathlessness and slight chest pain that pass on their own, to heart failure, cardiogenic shock, life-threatening rhythm disturbances and sudden cardiac death.<Cite n={2} />

<Diagram name="myocarditis">
  <p slot="normal">
    Myocarditis is inflammation of the heart muscle.<Cite n={1} /> Normally there are no areas of
    inflammation in the wall of the left ventricle (LV): it is uniform and contracts evenly.
  </p>
  <p slot="disease">
    In myocarditis the inflammation may be focal or diffuse.<Cite n={3} /> A heart ultrasound may
    show a wall thickened by oedema.<Cite n={1} /> The wall may move less well, and the pumping
    (systolic) function of the heart may be reduced.<Cite n={1} /> The weaker contraction in the
    animation shows one possible case. Where the areas sit in the diagram is arbitrary.
  </p>
</Diagram>

## Why it happens

<Patient>

Viruses are thought to be the most common cause of myocarditis.<Cite n={[1, 2]} /> They include enteroviruses, adenoviruses, parvovirus B19, some herpesviruses, and influenza and coronaviruses.<Cite n={1} /> There are also non-infectious causes: systemic and autoimmune diseases, reactions to medicines and toxic effects.<Cite n={[1, 2]} />

It mainly affects young and middle-aged people.<Cite n={2} />

</Patient>

<Student>

The 2025 ESC guideline introduces the working term inflammatory myopericardial syndrome (IMPS), an umbrella term used during the initial diagnostic process until a final diagnosis is made.<Cite n={1} /> Acute onset is defined as symptoms and signs lasting 4 weeks or less; chronic myocarditis is myocarditis persisting beyond 3 months.<Cite n={1} />

The most common infectious aetiology is presumed to be viral; enteroviruses, adenoviruses, parvovirus B19, some herpesviruses, and influenza and coronaviruses are the viruses most commonly associated with myocarditis.<Cite n={1} /> According to the Russian Ministry of Health guideline, viral infection is the most common cause of myocarditis in Europe and North America.<Cite n={2} /> Among non-infectious aetiologies the ESC lists systemic diseases, autoimmune disorders, and drug and toxic reactions, including immune checkpoint inhibitor-associated myocarditis.<Cite n={1} /> The Russian Ministry of Health guideline also names hypersensitivity reactions to some drugs and the cardiotoxicity of doxorubicin and other anthracyclines.<Cite n={2} />

One registry reported an incidence of 6.3–8.6 per 100 000 inhabitants, mostly in young men.<Cite n={1} />

</Student>

## Symptoms

<Patient>

The main symptom is chest pain, which more than 80% of people with myocarditis have.<Cite n={1} /> Breathlessness occurs in 20–50%, while tiredness, palpitations and fainting are less common, at about 5%.<Cite n={1} /> Myocarditis can also cause no symptoms at all.<Cite n={[1, 2]} />

A recent or current flu-like illness or gastroenteritis can make a doctor suspect myocarditis.<Cite n={1} /> In viral myocarditis, people usually see a doctor after 7–14 days of a mild flu-like illness.<Cite n={3} />

</Patient>

<Student>

The typical symptoms and signs at presentation are chest pain (more than 80% of cases) and dyspnoea (20–50%); fatigue, palpitations and syncope are less common, reported in about 5%.<Cite n={1} /> Asymptomatic cases may exist, for example vaccine- or drug-related ones.<Cite n={1} />

Fulminant myocarditis (3–9% of cases) is characterised by cardiogenic shock at presentation requiring haemodynamic support.<Cite n={1} /> The Russian Ministry of Health guideline describes it as a severe form of myocardial inflammation that develops rapidly as acute heart failure, cardiogenic shock or life-threatening rhythm disturbances.<Cite n={2} /> The first manifestation of myocarditis may be sudden death due to ventricular tachycardia.<Cite n={2} /> Myocardial inflammation with fatal arrhythmias is one of the causes of sudden cardiac death in young adults.<Cite n={1} />

</Student>

## How it is diagnosed

<Patient>

A blood test for troponin is done; troponin is a protein released into the blood when the heart muscle is damaged, and it is raised in myocarditis.<Cite n={1} /> The ECG is usually abnormal and may look like the ECG of a heart attack, so doctors rule out an acute coronary syndrome, for example by imaging the heart's arteries.<Cite n={[1, 2]} />

The basic test is a heart ultrasound (echocardiography).<Cite n={1} /> On its own it cannot always recognise myocarditis, because the ultrasound shows no signs specific to it.<Cite n={3} /> Inflammation in the heart muscle can be seen on a cardiac MRI; the final diagnosis is made by MRI or by a biopsy of the heart muscle.<Cite n={1} /> A biopsy is not done for everyone, only in particular situations where its result decides the treatment.<Cite n={1} />

</Patient>

<Student>

In acute myocarditis troponin T/I and creatine kinase MB (CK-MB) are elevated.<Cite n={1} /> Unlike in acute coronary syndrome (ACS), troponin in myocarditis usually falls slowly, which allows the likelihood of myocarditis to be judged in retrospect.<Cite n={2} />

The ECG is normal in only a minority of patients (about 15%); ST-segment elevation is the most frequent finding (57.5%), with other ST/T changes (23.5%) and conduction blocks (10%) less common.<Cite n={1} /> The picture can mimic myocardial infarction, with ST elevation in a non-coronary distribution.<Cite n={1} /> In its section on myocarditis presenting as acute coronary syndrome, the Russian Ministry of Health guideline reports ST elevation in two contiguous leads in 54% of cases; when the ST segment is elevated, coronary angiography or contrast-enhanced cardiac MRI is performed as standard.<Cite n={2} /> The ESC advises ruling out ACS whenever the patient's characteristics indicate it, with invasive coronary angiography or computed tomography angiography depending on clinical likelihood.<Cite n={1} />

Echocardiography is the basic imaging method; it might reveal increased wall thickness and echogenicity due to myocardial oedema.<Cite n={1} /> Myocarditis has no specific echocardiographic findings.<Cite n={3} /> Non-ischaemic myocardial inflammation is diagnosed by cardiac MRI according to the updated Lake Louise criteria: at least one T2-based criterion plus ideally one T1-based criterion.<Cite n={1} /> A definitive diagnosis can be based on cardiac MRI or on endomyocardial biopsy (EMB).<Cite n={1} />

EMB can detect the histological type of myocarditis and identify some specific aetiologies; it is needed when specific decisions depend on it.<Cite n={1} /> The Russian Ministry of Health guideline's absolute indications include haemodynamically unstable heart failure of less than 2 weeks' duration, and new-onset heart failure of 2 weeks to 3 months with a dilated left ventricle (LV), recurrent ventricular arrhythmias, second- or third-degree atrioventricular (AV) block, or no response to recommended therapy within 1–2 weeks; in all other situations EMB is only to be discussed.<Cite n={2} />

</Student>

## How it is treated

<Patient>

Treatment depends on the cause and severity of myocarditis, and the doctor chooses it together with the patient. In most cases treatment is supportive: its aim is to preserve the work of the left ventricle.<Cite n={3} /> If heart failure develops, it is treated according to heart failure guidelines.<Cite n={3} /> In cardiogenic shock that medicines cannot correct, machines that support the circulation are used; in severe cases a heart transplant is considered.<Cite n={3} />

Uncomplicated myocarditis, about 75% of cases, usually goes away on its own.<Cite n={1} /> In some people the heart's function gradually gets worse, which can lead to dilated cardiomyopathy.<Cite n={1} />

</Patient>

<Student>

The treatment approaches below follow the StatPearls review of viral myocarditis. Treatment is mostly supportive and aimed at preserving left ventricular function; patients with heart failure and ventricular dysfunction are treated according to current heart failure guidelines.<Cite n={3} /> In cardiogenic shock refractory to medical therapy, mechanical circulatory support should be considered: intra-aortic balloon pump counterpulsation, Impella or veno-arterial extracorporeal membrane oxygenation (ECMO).<Cite n={3} /> Cardiac transplantation is considered in some patients; it is only an option if a suitable donor is found.<Cite n={3} />

Uncomplicated cases (about 75% of unselected cases) usually have spontaneous remission.<Cite n={1} /> In acute myocarditis diagnosed by EMB, up to 50% of patients recover spontaneously, up to 25% may have persistent stable cardiac dysfunction, and 10–25% have progressive ventricular dysfunction that can lead to end-stage dilated cardiomyopathy.<Cite n={1} /> Subacute myocarditis may remit without residual damage or progress to chronic myocarditis or inflammatory cardiomyopathy.<Cite n={1} /> According to the Russian Ministry of Health guideline, progression to dilated cardiomyopathy is typical of the subacute form, and the outcome of acute myocarditis is largely determined by its aetiology, the severity of circulatory failure and how fast symptoms progress.<Cite n={2} />

Patients presenting with acute heart failure, particularly with an LV ejection fraction of 40% or less, are considered a high-risk group.<Cite n={1} /> Patients with advanced AV block or sustained ventricular arrhythmias are also considered high risk, even without LV dysfunction.<Cite n={1} />

</Student>

## When to call an ambulance

Myocarditis can be severe, with cardiogenic shock, acute heart failure and life-threatening rhythm disturbances.<Cite n={[1, 2]} /> Chest pain in myocarditis can resemble a heart attack, and so can the ECG, so the two can only be told apart by medical tests.<Cite n={1} /> Among the warning signs of myocarditis the ESC lists infarct-like chest pain, palpitations, symptoms of heart failure, fainting and haemodynamic instability.<Cite n={1} />

For chest pain, fainting, severe breathlessness, or palpitations with marked weakness or dizziness, call your local emergency number (112 in the EU, 911 in the US and Canada, 999 in the UK). This is the site's general safety rule, repeated at the bottom of every page.

<Quiz />