Myocarditis

and Martina Feichter, medical editor and biologist

Florian Tiefenböck studied human medicine at the LMU Munich. In March 2014, he joined as a student and has supported the editorial team with medical articles ever since. After receiving his medical license and practical work in internal medicine at the University Hospital Augsburg, he has been a permanent member of the team since December 2019 and, among other things, ensures the medical quality of the tools.

Brief overview

What is myocarditis? Inflammation of the heart muscle cells and usually of the surrounding tissue as well as the blood vessels supplying the heart (coronary arteries). If the inflammation also spreads to the pericardium, this is called perimyocarditis.
Symptoms: often no or hardly any noticeable symptoms such as increased palpitations (palpitations) and heart palpitations; Possibly chest pain, cardiac arrhythmias and signs of heart failure in advanced myocarditis (such as water retention in the lower legs)
Triggers: In infectious myocarditis, there are pathogens such as viruses (such as colds, flu, herpes, measles or Coxsackie viruses) or bacteria (e.g. the pathogens of tonsillitis, scarlet fever, diphtheria or blood poisoning). Non-infectious myocarditis occurs due to faulty immune reactions, radiation therapy or medication.
Risks: Possible consequences are a pathologically enlarged heart muscle (dilated cardiomyopathy) with chronic heart failure and severe cardiac arrhythmias. There is a risk of sudden cardiac death.
Treatment: above all physical rest and bed rest, possibly medication against the pathogens of infectious myocarditis (such as antibiotics against bacteria); Treatment of complications, e.g. heart-straining medication for heart failure (such as beta blockers)
Prognosis: With consistent physical restraint, the myocarditis usually heals without consequences. Otherwise there is a risk of long-term consequences such as cardiac insufficiency. Heart muscle inflammation is rarely fatal.

Myocarditis: Symptoms

Heart muscle inflammation is usually caused by viruses or bacteria (infectious myocarditis). The symptoms of such an infection therefore often precede myocarditis. These can be, for example, runny nose and cough, fever, headache and body aches. If these flu-like symptoms are accompanied by increasing tiredness and exhaustion, weakness, decreasing resilience or shortness of breath during exertion, the possibility of infectious myocarditis should always be considered.

In fact, these symptoms are often the only signs of the onset of acute myocarditis. Symptoms such as loss of appetite and weight as well as headaches and body aches can also occur. Other symptoms of myocarditis may include pain referred to as pain in the neck or shoulders.

If you develop possible symptoms of myocarditis days or weeks after a flu-like infection, you should definitely see a doctor!

Heart symptoms

Normally a healthy person does not feel his heart. However, when the heart muscle is inflamed, some people notice increased palpitations. Some also report a feeling of tightness in the chest (atypical angina pectoris) or heart palpitations. This stumbling expresses that the heart occasionally gets out of step for a moment:

The heart has a clock that is in the right atrium. From this so-called sinus node, in a healthy heart, the electrical signals spread evenly over the heart muscle and trigger its contraction. The heart beats in a coordinated manner and pumps the blood evenly into the body's circulation.

In the case of myocarditis, additional electrical signals are generated or their normal transmission is delayed. Sometimes the impulses are not even transmitted from the atrium to the ventricles (AV block). The normal heart rhythm is consequently disturbed. In some cases of inflammation of the heart muscle, this leads to a racing heart (tachycardia) or an irregular heart rhythm with interruptions.

Myocarditis: Triggers & Causes

With regard to the causes, a distinction is made between infectious and non-infectious myocarditis.

This happens with heart muscle inflammation

The mostly painless myocarditis can considerably weaken the heart muscle and trigger cardiac arrhythmias.

Infectious myocarditis

Myocarditis is called infectious if it is caused by pathogens. Viruses are involved in around 50 percent of the cases. Infectious myocarditis is often preceded by a banal viral infection (cold, flu-like infection, diarrhea). The so-called Coxsackie B virus in particular is often the cause of viral myocarditis. But many other viruses such as the causative agents of herpes, flu (influenza), mumps, rubella or measles can cause myocarditis.

If viral myocarditis is suspected, the causative virus is only determined in exceptional cases. That would be of little practical use - there are usually no specific drugs against the viruses in question.

Bacteria can also cause myocarditis. Especially in the context of bacterial blood poisoning (sepsis), in which the heart valves are already affected, the inflammation can also spread to the heart muscle. Typical pathogens here are so-called staphylococci. Another group of bacteria, the streptococci, can also cause myocarditis. This includes, for example, the causative agents of scarlet fever or tonsillitis.

Another bacterial cause of myocarditis can be diphtheria. Lyme disease is rarely to blame for an inflamed heart muscle. Their pathogen, the Borrelia burgdorferi bacterium, is transmitted through a tick bite.

Fungal infections are also rarely the trigger for an infectious heart muscle inflammation: Fungi usually only trigger myocarditis if the patient's immune system is significantly weakened. This is the case, for example, with AIDS, chemotherapy or the use of immunosuppressive drugs.

Other rare pathogens that cause myocarditis are parasites such as the fox tapeworm or unicellular organisms such as toxoplasmosis or Chagas disease.

Non-infectious myocarditis

In a non-infectious heart muscle inflammation, no pathogens are the trigger. Instead, the cause is, for example, a dysregulation of the immune system. The immune system is directed against the body's own structures, so that so-called autoimmune diseases develop. These include, for example, vascular inflammation, connective tissue inflammation and rheumatic diseases. Such autoimmune diseases can also lead to heart muscle inflammation (autoimmune myocarditis).

Another cause of non-infectious heart muscle inflammation is radiation to the chest as part of radiation therapy for various cancers (such as lung cancer).

Drugs rarely cause non-infectious myocarditis. These can be, for example, the antibiotics penicillin and ampicillin, the diuretic drug hydrochlorothiazide and the blood pressure lowering drug methyldopa.

If you can't find a trigger for the heart muscle inflammation at all, the doctor speaks of the so-called idiopathic Fiedler myocarditis.

Myocarditis: Risks

Heart muscle inflammation harbors serious dangers - especially if those affected do not take enough care of themselves or have a previously damaged heart. This is because myocarditis can cause severe cardiac arrhythmias. These have significant consequences for the cycle. Because the heart needs a calm, steady rhythm to fill with blood again after each heartbeat for the next powerful contraction.If it beats too quickly or irregularly due to myocarditis, it cannot fill or empty properly. The possible consequence is a circulatory collapse with sudden cardiac death.

In about every sixth patient, myocarditis triggers remodeling processes in the heart, which ultimately lead to chronic cardiac insufficiency: the damaged heart muscle cells are remodeled into scar tissue (fibrosis), the heart cavities (chambers, atria) expand. Doctors speak of dilated cardiomyopathy here. The walls of the abnormally enlarged heart muscle are to a certain extent "worn out" so that they can no longer contract powerfully. So a permanent heart failure has developed. In severe cases, the heart's pumping capacity can collapse completely. Sudden cardiac death can also occur here.

Myocarditis: examinations and diagnosis

If you suspect heart muscle inflammation, your family doctor or a specialist in cardiology is the right contact. If necessary, the doctor will refer you to a hospital for further examinations.

Doctor-patient conversation

The doctor will first talk to you in detail to collect your medical history (anamnesis). He asks about the exact symptoms and whether they were possibly preceded by an infection (cold, flu, diarrhea, etc.). The doctor will also ask whether you have any underlying medical conditions (particularly heart disease) or whether you have already had heart surgery.

Physical examination

This is followed by a thorough physical examination. The doctor will, among other things, listen to your heart and lungs with the stethoscope, tap your chest and measure your pulse and blood pressure. He will also check whether you are showing any signs of the onset of heart failure. These include, for example, water retention (edema) in the lower legs.

EKG (electrocardiography)

Another important examination is the measurement of the electrical activity of the heart muscle (electrocardiography, EKG). Changes in cardiac activity, such as those that occur in an inflammation of the heart muscle, can be detected. An accelerated heartbeat (palpitations) and additional beats (extrasystoles) are typical. Cardiac arrhythmias are also possible. Since the deviations usually only occur temporarily, a long-term measurement of the heart activity (long-term ECG) is advisable - in addition to the usual short-term resting ECG.

Cardiac ultrasound

Using an ultrasound examination of the heart (echocardiography), the doctor can assess the structure and function of the heart muscle. For example, he can detect enlarged heart chambers or a pump weakness. In some cases of myocarditis, fluid also collects between the pericardium and the heart muscle. Such a pericardial effusion can also be detected on ultrasound.

Blood test

Inflammation values in the blood (CRP, ESR, leukocytes) show whether there is inflammation in the body. Heart enzymes such as troponin-T or creatine kinase are also determined: They are released from the cells when heart muscle cells are damaged (e.g. as a result of myocarditis) and are then detectable in increased amounts in the blood.

If antibodies against certain viruses or bacteria are found in the blood, this indicates a corresponding infection. If the heart muscle inflammation is the result of an autoimmune reaction, corresponding autoantibodies (antibodies against the body's own structures) can be detected.

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A chest x-ray (chest x-ray) can be used to identify signs of myocarditis-related cardiac insufficiency. The heart is then enlarged. In addition, a backlog of fluid in the lungs can be visible, which is caused by the weak pumping power of the heart.

Magnetic resonance imaging (MRI)

Using magnetic resonance imaging (magnetic resonance imaging), the doctor can differentiate between inflamed and damaged areas of the heart from healthy ones. An MRI scan of the heart is called a cardiac MRI.

Tissue removal using a cardiac catheter

Sometimes an examination using a cardiac catheter is also done if the heart muscle is inflamed. A small tissue sample can be taken from the heart muscle (myocardial biopsy). It is examined in the laboratory for inflammatory cells and pathogens.

Myocarditis: Treatment

The treatment of myocarditis depends on the one hand on the symptoms and on the other hand on the trigger. Physical rest and the treatment of a possible underlying disease are the cornerstones of myocarditis treatment.

If the heart muscle inflammation is very severe, the patient must be treated in the intensive care unit. Vital parameters such as cardiac activity, pulse, oxygen saturation and blood pressure can be continuously monitored there.

Physical conservation

It is particularly important in the case of cardiac muscle inflammation that the patient spares himself completely. This means that he must avoid any physical exertion, for example around the house. Because an inflammation of the myocardium can cause lifelong damage to the heart muscle and the heart valves if it is further fueled by stress.

If the heart muscle is severe, patients are admitted to the hospital.

Even weeks after the acute phase of the disease, the patient must not overexert himself. The doctor decides when full exercise is possible again. As long as there are signs of heart failure, the patient is unable to work. If he stresses himself again prematurely, he risks a relapse and permanent damage.

If myocarditis requires prolonged bed rest, there is a risk of blood clots forming (thrombosis). Patients are given anticoagulants as a preventive measure.

Treatment of the cause

Viruses are the most common cause of infectious myocarditis. However, there are usually no antiviral drugs available for such viral myocarditis. The treatment here essentially consists of rest and bed rest.

The situation is different with bacterial myocarditis: the doctor prescribes antibiotics against the triggering bacteria. Targeted drugs can also be used against other pathogens, which in rare cases cause myocarditis. These include antimycotics against fungal infections and antiprotozoics against single-cell parasites (such as the causative agents of Chagas disease).

In certain cases, other therapies can be considered for heart muscle inflammation (sometimes only in the context of studies). This can be, for example, the administration of cortisone. It has anti-inflammatory effects and suppresses the immune system. This can be useful in the case of myocarditis, in which antibodies are formed against the body's own structures due to a dysregulation of the immune system (autoantibodies).

Treatment of complications

One possible complication of heart muscle inflammation is heart failure. Then the doctor can prescribe various medications, for example ACE inhibitors, AT1 receptor antagonists or beta blockers. They relieve the weak heart. The same thing is done by water-boosting drugs (diuretics).

Sometimes the heart beats so irregularly and quickly in myocarditis that a life-threatening arrhythmia such as ventricular tachycardia or ventricular fibrillation threatens. In this case, patients may be temporarily supplied with an external shock generator (defibrillator). In the event of ventricular fibrillation, the device automatically emits a strong electrical impulse to restore normal heart rhythm. Fortunately, this measure is seldom necessary.

If fluid has accumulated in the pericardium during an inflammation of the heart muscle (pericardial effusion), this should be suctioned off with a thin, hollow needle (pericardial puncture).

In the worst case, myocarditis damages the heart so severely and permanently that it can no longer maintain its function. Then the patient needs a donor heart (heart transplant).

Myocarditis: disease course and prognosis

Myocarditis can occur at any age and can affect young people with healthy hearts. If patients consistently take physical care, the disease progression and prognosis are usually good. Overall, myocarditis heals in more than 80 percent of cases without leaving any permanent damage. This is especially true with viral myocarditis. In some patients, harmless extra heart beats can then be found on the ECG (electrocardiogram).

The problem with myocarditis is that it sometimes hardly causes any symptoms. Many patients therefore do not take sufficient care of themselves. This is particularly noticeable in young people who do sports despite heart muscle inflammation. The possible consequences are severe cardiac arrhythmias that can lead to sudden cardiac death. However, that rarely happens.

Myocarditis: duration

Acute myocarditis lasts about six weeks on average. In individual cases, the duration of the illness depends on the extent of the inflammation and the general health of the patient.

It is also very difficult to tell when myocarditis has really completely healed. Even if a person concerned feels completely healthy again after having overcome myocarditis, they should take a few weeks' rest and avoid physical exertion. This is the only way to avoid serious late effects (such as cardiac insufficiency).

Chronic myocarditis

In some patients, myocarditis is chronic. The heart muscle or the heart chamber (especially on the left side) is enlarged (dilated cardiomyopathy). The chamber walls are noticeably thin and can no longer apply the necessary pumping force. As a result, the heart is restricted in its function - heart failure (heart failure) has developed. Even minor exertion (such as climbing stairs) causes the person concerned to experience difficulty breathing (dyspnoea). The heart failure usually needs to be treated with medication.

Myocarditis: Prevention

Heart muscle inflammation can be prevented by vaccinating against causative infectious diseases and having these vaccinations refreshed as planned. You should follow the recommendations of the Standing Vaccination Commission (STIKO) at the Robert Koch Institute. For example, vaccination against diphtheria is advisable. In addition to the risk of myocarditis, this bacterial infectious disease also carries other dangers such as severe pneumonia. In childhood, the vaccination is usually given together with those against tetanus and polio.

It is also very important to cure flu-like infections properly. With any fever, physical exertion should be consistently avoided. The same applies even to a seemingly harmless cold. If you "drag out" such an infection, the pathogens (viruses or bacteria) can easily spread to the heart and trigger myocarditis.

People who have had myocarditis before are particularly at risk of getting it again (relapse). You should therefore be particularly careful. Above all, the combination of physical exertion, stress and alcohol should be avoided. In addition, bacterial inflammation of the skin and mucous membranes should be treated early with antibiotics. Such diseases are often the trigger for heart muscle inflammation again.