Medical history is essential for suspecting myocarditis, as it allows the identification of predisposing factors and the differentiation of this condition from other cardiac or systemic diseases. It is crucial to collect information about recent infections, cardiovascular history, exposure to toxins, and the presence of autoimmune or systemic diseases.
History of infections: It is necessary to assess whether, in the weeks preceding symptom onset, the patient experienced infections, especially of viral origin (such as the common cold, pharyngitis, influenza, or gastroenteritis) in which viruses such as Coxsackievirus, Adenovirus, and Parvovirus B19—known for their myocardial tropism—may have acted. Bacterial infections (e.g., by beta-hemolytic Streptococcus or Borrelia burgdorferi in Lyme disease) and, in patients who have traveled to endemic areas, parasitic infections (such as Chagas disease by Trypanosoma cruzi) are also relevant.
Cardiac history: It is important to determine whether the patient has a history of cardiac diseases, such as previous episodes of chest pain, palpitations, arrhythmias, signs of heart failure, or previous myocarditis/pericarditis. A patient without prior cardiac history who develops suspicious symptoms has a higher risk of acute inflammatory events, while in those with known heart disease it is essential to rule out worsening of the preexisting condition.
Toxicological and pharmacological history: Assessment should include the use of cardiotoxic drugs (for example, certain chemotherapeutics and immunosuppressants) and possible hypersensitivity reactions to antibiotics or NSAIDs, which may induce eosinophilic myocarditis. Alcohol or drug abuse (such as cocaine and amphetamines) and exposure to heavy metals or toxic chemicals are further risk factors.
Autoimmune or systemic diseases: Information should be collected about diseases such as systemic lupus erythematosus, scleroderma, or Churg-Strauss syndrome, as these conditions can cause immune-mediated myocarditis. The presence of systemic symptoms (cutaneous rash, arthralgia, eosinophilia) may suggest specific forms such as eosinophilic myocarditis.
A detailed medical history allows for the identification of key elements for diagnostic suspicion and directs subsequent investigations, facilitating rapid diagnosis in patients with acute cardiac symptoms and a recent history of infections, toxin exposure, or systemic diseases.
Clinical manifestations in myocarditis are extremely heterogeneous and vary according to the intensity of inflammation and the extent of myocardial injury.
Myocarditis presents a spectrum of general symptoms common to all infectious diseases, related to the systemic response to infection, such as fever, general malaise, asthenia, bone and muscle pain, as well as more specific symptoms related to myocardial involvement, including:
Myocarditis should be suspected when, following a recent infection or toxin exposure, the patient presents with symptoms such as chest pain, dyspnea, palpitations, and fever, associated with clinical findings such as disproportionate tachycardia and signs of heart failure.
A detailed medical history, integrated with these clinical elements, directs diagnostic suspicion and the need for further investigations.
There are also forms of asymptomatic or subclinical myocarditis, in which the patient does not manifest obvious signs or symptoms. These forms may be incidentally detected through imaging studies performed for other reasons but often represent a condition that does not require specific therapeutic interventions, although it is important to monitor their progression.