The incidence of myocarditis is currently increasing, largely due to advances in molecular techniques. It is known to affect a considerable number of people worldwide, with a prevalence estimated to range between 8 and 10 per 100,000; this figure is likely higher due to undiagnosed cases: silent cases, sudden death, diagnostic complexity.
Myocarditis was defined in 1995 by the World Health Organization (WHO) as an inflammatory disease of the heart muscle (myocardium). It can occur due to exposure to external agents (viruses, bacteria, toxins, etc.) or internal factors (autoimmune diseases). The most frequent cause in the developed world is viruses. The function of cardiac muscle tissue (myocardium) is to pump blood throughout the body. Myocarditis can weaken the heart, compromising its ability to pump blood efficiently and potentially causing abnormal heart rhythm disorders (arrhythmias).
Myocarditis can affect people of all ages, and its severity ranges from mild cases, which resolve without complications, to more severe cases that can lead to certain complications. Early detection and appropriate treatment are crucial to prevent long-term complications and improve the patient’s prognosis.
Symptoms of myocarditis
The symptoms of myocarditis can be very diverse, ranging from mild and nonspecific to severe. Some patients may not experience any symptoms at all, remaining asymptomatic, which makes diagnosis difficult, or they are referred because they have abnormalities in an electrocardiogram (ECG) or echocardiogram performed for another reason.
Early symptoms:
these may include chest pain, shortness of breath (dyspnea), fatigue, a feeling of rapid or irregular heartbeat (palpitations), and fluid retention with swelling of the legs and feet.
Late symptoms:
in more severe cases, myocarditis can lead to heart failure, severe arrhythmias, and even sudden death.
It is important to note that these symptoms may be indicative of other cardiac conditions. Therefore, it is essential to seek medical attention if you experience any of these symptoms.
Classification of myocarditis
Myocarditis is classified in various ways, allowing healthcare professionals to better understand the nature and extent of the inflammation:
According to the cause: this classification distinguishes between infectious myocarditis, caused by viruses, bacteria, fungi, or parasites, and noninfectious myocarditis, which can be autoimmune, toxic, or induced by drugs or radiotherapy. Physical agents: Heat stroke or hypothermia.
According to the course: it is classified as fulminant (sudden and severe onset), acute (short duration), or chronic (persistent). This classification helps to determine the level of urgency of treatment and the prognosis.
According to histology (microscopic study of cardiac tissue): it is subdivided into lymphocytic, eosinophilic, giant cell, and granulomatous types. This classification is essential for accurate diagnosis and targeted treatment.
Causes of myocarditis
Viral infections are the most frequent cause of myocarditis, especially Coxsackie virus, adenovirus, parvovirus B19, cytomegalovirus, herpes simplex virus, human immunodeficiency virus (HIV), and coronavirus (SARS-CoV-2). However, there are other less common causes, including:
Bacterial, fungal, or parasitic infections: although less frequent than viral infections, these infections can also cause inflammation of the myocardium.
Autoimmune diseases: diseases such as systemic lupus erythematosus and rheumatoid arthritis can affect the heart and cause myocarditis.
Drug reactions: some medications, such as certain antibiotics, nonsteroidal anti-inflammatory drugs, and chemotherapy drugs, can trigger an inflammatory reaction in the myocardium.
Exposure to toxins: exposure to heavy metals, radiation, and certain chemicals can also cause myocarditis.
There are various factors that can increase the likelihood of developing myocarditis. Some of these factors are modifiable, while others are not. Among the different risk factors are:
Weakened immune system: people with HIV/AIDS, organ transplant recipients, or those receiving chemotherapy have a higher risk of developing myocarditis.
Recent viral infection: a viral infection, even a mild one, can predispose one to the development of myocarditis.
Exposure to certain toxins or medications: as mentioned previously, exposure to certain substances can trigger myocarditis.
Complications of myocarditis
Myocarditis, if not treated properly, can lead to serious complications that affect long-term health:
Heart failure: inflammation of the myocardium can weaken the heart, impairing its ability to pump blood efficiently. This can lead to fluid buildup in the lungs and extremities, causing shortness of breath and swelling.
Arrhythmias: myocarditis can disrupt the heart’s electrical system, causing irregular heartbeats. These arrhythmias can be mild or severe, such as ventricular fibrillation.
Blood clots: inflammation of the myocardium can lead to the formation of blood clots in the heart. These clots can break off and travel to other parts of the body, obstructing blood flow and causing a stroke or pulmonary embolism.
Sudden cardiac death: in rare cases, myocarditis can cause sudden death due to severe arrhythmias or acute heart failure.
It is crucial to seek medical attention if myocarditis is suspected in order to prevent these complications.
Diagnosis of myocarditis
Diagnosing myocarditis can be challenging due to the similarity of its symptoms to other heart conditions. An accurate diagnosis requires a combination of tests and assessments, including:
Blood tests: blood tests are performed to detect inflammatory markers such as C-reactive protein (CRP) and erythrocyte sedimentation rate (ESR), as well as to rule out other causes of the symptoms. Tests can also be performed to detect specific viral infections.
Electrocardiogram (ECG): the ECG records the electrical activity of the heart and can show abnormal heart rhythms, such as tachycardia, bradycardia, or ventricular arrhythmias. It can also reveal signs of damage to the myocardium.
Echocardiogram: this test uses sound waves (ultrasound) to create images of the heart in motion. An echocardiogram can show the size and shape of the heart, the function of the heart valves, and the strength of the heart muscle contractions (ejection fraction). It can also detect the presence of fluid around the heart (pericardial effusion).
Cardiac magnetic resonance imaging (MRI): cardiac MRI provides detailed images of the heart and is able to detect areas of interstitial edema and the myocardial inflammatory reaction associated with viral infection. It is a non-invasive test that uses magnetic fields and radio waves, considered the best non-invasive diagnostic technique available for the diagnosis of acute myocarditis and for monitoring the response to treatment.
Endomyocardial biopsy: in some cases, an endomyocardial biopsy may be performed to confirm the diagnosis. This procedure involves inserting a catheter through a vein into the heart to extract a small sample of myocardial tissue. The sample is examined under a microscope to detect signs of inflammation.
HM Hospitales has the technology and specialists necessary for an accurate diagnosis of myocarditis.
Myocarditis treatments
The treatment of myocarditis focuses on addressing the underlying cause of inflammation, controlling symptoms, and preventing long-term complications. The therapeutic approach varies depending on the cause, the severity of the inflammation, and the presence of complications such as heart failure or arrhythmias.
Infectious myocarditis: treatment is aimed at eradicating the infectious agent. If the cause is viral, there is generally no specific antiviral treatment, and management focuses on symptom relief and cardiac support. However, if a virus susceptible to antiviral treatment is identified, the appropriate drug will be administered. Bacterial myocarditis is treated with antibiotics specific to the type of bacteria responsible, while fungal myocarditis is treated with antifungals and parasitic myocarditis with antiparasitics.
Non-infectious myocarditis: treatment focuses on controlling inflammation and modulating the immune system’s response. In cases associated with autoimmune diseases, immunosuppressants, such as corticosteroids or thiopurines, can be used to reduce inflammation and suppress the immune response. The use of these medications should be carefully evaluated and monitored by a specialist, due to their potential side effects. If myocarditis is a reaction to a medication, the suspected drug should be discontinued immediately.
Myocarditis that has causedheart failure: the treatment focuses on improving heart function and relieving symptoms. Medications such as angiotensin-converting enzyme (ACE) inhibitors are used to relax blood vessels and reduce the workload of the heart. Angiotensin II receptor blockers (ARBs) have a similar effect. Beta-blockers reduce heart rate and blood pressure, decreasing the workload on the heart. Diuretics help eliminate excess fluid, relieving swelling and shortness of breath. Mineralocorticoid receptor antagonists (MRAs) block the effects of aldosterone, a hormone that can worsen heart failure. Sodium-glucose cotransporter 2 (SGLT2) inhibitors.
If there are arrhythmias, treatment focuses on controlling heart rate and preventing complications. Beta-blockers help control heart rate and reduce the risk of arrhythmias. Other antiarrhythmic drugs may also be used, depending on the type of arrhythmia.
Other treatments: in addition to pharmacological treatment, rest is recommended during the acute phase for heart recovery. Restricting fluids and salt helps reduce the workload on the heart and prevents fluid retention.
Ventricular assist devices (VADs): in cases of severe heart failure that does not respond to medical treatment, VADs, such as mechanical circulatory support, can be used. These devices help the heart pump blood, providing temporary or long-term circulatory support, depending on the severity of the condition and the possibility of myocardial recovery. There are different types of VADs, such as continuous-flow or pulsatile VADs, and the choice of the appropriate device is based on the individual needs of each patient. Mechanical circulatory support can be a bridge to transplantation or a definitive therapy in some cases.
Heart transplant: it is considered in extreme situations, when myocarditis has caused irreversible and severe damage to the heart, and other treatment options have failed. It is a complex procedure that involves replacing the damaged heart with a healthy donor heart. The decision to perform a heart transplant is made after a thorough evaluation of the patient and careful consideration of the risks and benefits of the procedure.
The management of myocarditis often requires a multidisciplinary approach, involving cardiologists, infectious disease specialists, immunologists, and other healthcare professionals. HM Hospitales has a comprehensive specialized Cardiology center that works in a coordinated manner to provide integrated management of the needs and requirements of different types of heart conditions.https://www.hmhospitales.com/hm-ciec/
Remember that this article is for informational purposes only and does not replace professional medical advice. If you suspect you have myocarditis, consult a specialist to obtain an accurate diagnosis and an appropriate treatment plan tailored to your needs.
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