Cardiomyopathy is a disease of the heart muscle that impairs contraction, ultimately reducing the heart’s ability to pump blood.
It includes myocarditis, an inflammation of the heart muscle called the myocardium.
It can affect the entire heart or be limited to certain areas.
In some cases it is entirely benign, with people experiencing almost no symptoms. It can also be very severe and lead to heart failure or ventricular arrhythmia, which is an abnormal heart rhythm that can lead to sudden death.
The causes of myocarditis are not always identified. However, in most cases, myocarditis is linked to a viral infection such as the flu, herpes, COVID-19, AIDS or hepatitis C.
Along with viruses, certain bacteria can trigger myocarditis in rare instances. These include those responsible for diphtheria and Lyme disease.
Besides infections, myocarditis can also be caused by autoimmune diseases like lupus and rheumatoid arthritis.
It can be linked to medication, chemotherapy, or even vaccine reactions. Finally, the condition can also be caused by alcohol consumption and drug use.
There are several types of myocarditis. It can be classified as lymphocytic, eosinophils (when white blood cells enter the myocardium), giant cell (often due to autoimmune disease), or fulminant (the most severe form, characterized by sudden and severe inflammation).
Symptoms
Symptoms of myocarditis can vary greatly from person to person, ranging from mild, even imperceptible, to severe.
They can include shortness of breath, especially during physical activity. Some people may also suffer from dizziness or even fainting during or shortly after physical activity due to a lack of oxygen reaching the brain.
Chest pain at rest and during physical activity can also occur. Finally, some people experience palpitations, the sensation of a rapid or irregular heartbeat.
Edema may also develop, causing swelling in the hands, ankles or legs.
When myocarditis is caused by an infection, symptoms can include fever, pain or a rash.
Diagnosis
The patient should consult a primary care physician, who will make an initial diagnosis before recommending further examinations.
An electrocardiogram is used to detect arrhythmia and indicate any additional tests that are required.
Echocardiography, which uses ultrasound, is the most reliable tool for detecting myocarditis. Magnetic Resonance Imaging (MRI) confirms the diagnosis.
Magnetic Resonance Imaging (MRI) confirms the diagnosis of inflammation in the heart muscle.
Cardiac catheterization is used to identify narrowed blood vessels or collect samples of tissue if necessary.
Treatment
Medication such as beta-blockers can initially be prescribed to treat myocarditis by slowing down the heart rate and protecting the heart muscle. Antiarrhythmics can also be used to correct certain rhythm disorders.
Medical devices, such as implantable cardioverter-defibrillators can be fitted to prevent cardiac arrest related to ventricular arrhythmia.
In the most acute cases, when neither medication nor medical devices are effective, a heart transplant may be considered.
Lifestyle changes are also recommended for people with myocarditis. In addition to regular check-ups with a cardiologist, they should limit physical activity, typically for six months, to give the heart time to heal.
More generally, a set of simple measures can help prevent most types of myocarditis: staying up to date with vaccinations, following treatment plans for autoimmune diseases, maintaining a low-salt, low-fat diet, practicing good hygiene and avoiding drug use and excessive alcohol consumption.
What is an implantable cardioverter-defibrillator?
The implantable cardioverter-defibrillator referred to in this article is a small device connected to leads that are often secured to the heart with screws. It should not be confused with an automated external defibrillator, which is used to revive victims of cardiac arrest.
Reviewed and approved by Benjamin Bouyer, MD, Cardiologist at Bordeaux University Hospital (CHU)
