Heart Muscle Inflammation (Myocarditis): Cause and Symptoms

Inflammation of the heart muscles is not to be trifled with. Although in many cases it goes unnoticed, it is not uncommon for it to be found at autopsy in people with an unexplained cause of death. The symptoms are often quite non-specific – which is precisely why myocarditis is so difficult to detect. No one knows exactly how common myocarditis really is – the number of undetected cases is very high. But in autopsies of young adults who die suddenly, about 10 percent of their deaths are attributed to myocarditis; in children, the figure is as high as 16 to 21 percent.

Causes of heart muscle inflammation

The causes of heart muscle inflammation are varied. It can be triggered by an infection with a wide variety of pathogens – viruses, bacteria, protozoa, parasites and fungi – or be the result of an exaggerated defense reaction (autoimmune reaction). A well-known example is the common cold. Anyone who exercises despite a cold and does not take sufficient rest risks the pathogens migrating through the body to the heart and triggering an inflammation there.

Myocarditis can also be caused by chemical, potentially toxic substances (for example, drugs or medications such as certain antibiotics or chemotherapeutic agents) or physical stimuli (for example, radiation). In addition, myocarditis can occur after a heart attack and heart surgery.

In our latitudes, by far the most common cause is a viral infection, usually with Coxsackie virus type B. The inflammation that follows the infection and corresponding immune response destroys the heart muscle cells, the connective tissue surrounding them, and the small vessels within them. Sometimes the inflammation also spreads to the pericardium – this is called perimyocarditis.

Recognizing symptoms of myocarditis

The symptoms of myocarditis are quite nonspecific – which is what makes it so difficult to diagnose. Sufferers often report a previous upper respiratory tract infection with associated symptoms. Myocarditis itself, for one, can manifest itself through general symptom:

  • Performance kink and feeling of weakness
  • Fatigability
  • Fever
  • Restlessness
  • But also joint and muscle pain

These are all symptoms that resemble flu or cold and then often attributed to a respiratory infection. In addition, however, other symptoms are possible, which affect the heart.

Signs are not always present in the heart

Signs specific to the heart are not always present due to arrhythmias, irritation of the pericardium, and impaired cardiac output (insufficiency):

  • Accelerated pulse (even without physical exertion).
  • Racing or stumbling heart
  • Shortness of breath during exertion
  • Feeling of pressure or pain in the chest
  • Dizziness and fainting spells

The most common of these complaints are fatigue and shortness of breath, followed by palpitations and chest pain.

Myocarditis: severe course possible

In the worst case – in a very acute course – a life-threatening heart failure can develop within a short time; also pronounced cardiac arrhythmias can lead to sudden cardiac death. Such severe courses occur in one third of patients with virus-induced myocarditis.

In another third, the acute form develops into a chronic form, i.e. it does not heal completely and permanently impairs cardiac function. The remaining affected individuals recover completely or mostly from myocarditis.