Emergent Care / Stabilization:
Any patient presenting with symptoms concerning for myocarditis or myopericarditis should be referred to the emergency department (ED) immediately. There is extensive overlap between the inflammatory states of the heart and acute coronary syndrome (ACS) / myocardial infarction. Fulminant myocarditis refers to a range of severe signs and symptoms, from heart failure to cardiogenic shock.

These patients should be directed to an ED that has access to coronary catheterization as they might be candidates for acute coronary intervention. Before the diagnosis of myocarditis or myopericarditis can be considered, ACS / myocardial infarction must be ruled out.

Blood cultures should be drawn in febrile patients to rule out bacteremia and endocarditis.

Diagnosis Overview:
Myocarditis is inflammation of the myocardium.

Myopericarditis is inflammation of the pericardium with concurrent involvement of the adjacent myocardial layer.

Both disease processes can be caused by an underlying infectious or noninfectious etiology.

Infectious agents: Viral infections are the most frequent causes of myocarditis / myopericarditis. Coxsackievirus B, enteroviruses, adenoviruses, and parvovirus B19 are among the most common agents. Other infectious agents, such as bacteria, fungi, and parasites, can also cause myopericarditis.

Autoimmune diseases: In some cases, myocarditis / myopericarditis can result from an autoimmune response, where the immune system mistakenly targets the heart tissue. Common conditions such as systemic lupus erythematosus (SLE) and rheumatoid arthritis have been associated, as well as a wide range of systemic diseases including sarcoidosis, amyloidosis, and hemochromatosis.

Medications and toxins: Certain medications and toxins, such as antibiotics (eg, penicillin), NSAIDs, chemotherapeutic agents, and recreational drugs (eg, cocaine and methamphetamine), can cause myocarditis / myopericarditis.

Radiation therapy: Previous radiation therapy to the chest or surrounding tissues can cause myocarditis / myopericarditis as a late side effect.

Trauma: Myocarditis / myopericarditis can be caused by blunt chest injuries from a motor vehicle crash, fall, or sports-related incident.

Physical Symptoms:
Myocarditis and myopericarditis can present with a wide range of symptoms. The severity and specific symptoms can vary from person to person. Some symptoms may include:

Chest pain: This is the most common symptom of myocarditis / myopericarditis. The chest pain may be sharp, stabbing, or a dull ache that is typically substernal. The pain can sometimes radiate to the neck, arms, or back. When the pericardium is involved, some patients may describe positional chest pain and improvement in symptoms when leaning forward.

Dyspnea / hypoxia: Myocarditis commonly produces signs and symptoms similar to heart failure, such as pulmonary edema or lower extremity edema.

Fatigue and weakness: Individuals with myocarditis may experience persistent fatigue, weakness, or a general feeling of being unwell.

Palpitations: Some individuals may experience irregular heartbeats, rapid heart rates, or a sensation of fluttering in the chest.

Flu-like symptoms: In viral myocarditis / myopericarditis, individuals may initially experience symptoms similar to influenza, including fever, body aches, headache, sore throat, and general malaise.

Most patients with myocarditis will experience complete resolution of myocardial inflammation and subsequent injury. Uncommon, although potentially devastating, are patients who present in severe heart failure and/or cardiogenic shock. Others will have residual cardiac dysfunction with manifestations of congestive heart failure.

Unlike isolated myocarditis, myopericarditis does not typically lead to poor long-term cardiovascular outcomes, such as congestive heart failure, as most patients are expected to have a full recovery. NSAIDs are often effective therapy. For pericarditis, colchicine should also be considered.