When myocarditis is suspected, it is essential to follow a stepwise diagnostic pathway, starting from initial screening tests and proceeding to advanced investigations to confirm the diagnosis and assess the severity and etiology of the disease.
Initial Phase (First Level)
In this phase, non-invasive and readily available tests are performed, useful for providing preliminary indications of myocardial injury:
Electrocardiogram (ECG): detects electrical abnormalities, rhythm disturbances, and indirect signs of ischemia.
Blood tests: assessment of biomarkers (troponin, CK-MB, BNP) and inflammatory markers (CRP, ESR) to indicate myocardial injury and inflammatory response.
Chest X-ray: useful for identifying signs of heart failure and related pulmonary abnormalities.
Echocardiography: first-line test to evaluate ventricular function, regional wall motion, and to detect effusion or signs of heart failure.
Diagnostic Confirmation Phase (Second Level)
If initial data are suggestive, more in-depth investigations are performed to achieve a definitive diagnosis:
Cardiac Magnetic Resonance (CMR): provides detailed images to identify edema, inflammatory infiltrates, and fibrosis, applying the Lake Louise criteria.
Endomyocardial Biopsy: an invasive test, reserved for selected cases, that allows for histopathological diagnosis and analysis of the inflammatory infiltrate according to the Dallas criteria.
Severity Assessment and Follow-Up Phase (Third Level)
Once myocarditis is confirmed, further tests help define the extent of damage, the severity of the disease, and guide therapeutic planning:
Exercise testing: performed during follow-up to evaluate the functional reserve of the heart and response to stress.
Immunological and serological tests: aimed at identifying autoimmune markers or specific pathogens, useful for characterizing the etiology of myocarditis.
Integration of the results obtained in these phases allows for an accurate definition of the diagnosis, severity, and origin of myocarditis, guiding the therapeutic pathway and clinical monitoring of the patient.
Treatment
The treatment of myocarditis varies according to etiology, severity, and the presence of complications. The therapeutic approach is divided into several phases: initial supportive therapy, etiology-specific treatment, and, in the most severe cases, advanced therapies.
Supportive Therapy
During the acute phase of myocarditis, when cardiac function is impaired, the focus is on supporting cardiac function and controlling symptoms:
Drugs for heart failure: ACE inhibitors, beta-blockers, and diuretics are used to improve ventricular function and reduce cardiac workload.
Inotropic support: In patients with severe cardiac dysfunction, the use of inotropic agents helps sustain myocardial contractility.
Arrhythmia management: Antiarrhythmic drugs and, in selected cases, electrical cardioversion, to control rhythm disturbances.
In stable cases of myocarditis, without impaired cardiac function, these therapies are not required.
Specific Therapy
Targeted treatment varies according to the etiology of myocarditis and can be summarized as follows:
Viral myocarditis: Supportive therapy is generally adopted, as there are no universally effective specific antivirals; in selected cases, immunomodulators may be considered.
Bacterial myocarditis: Treated with targeted antibiotics, chosen based on the isolated or suspected pathogen, in addition to supportive therapy for cardiac function and monitoring of infectious complications.
Fungal myocarditis: Although rare, it requires treatment with specific antifungals, especially in immunocompromised patients, together with careful hemodynamic support.
Parasitic myocarditis: In the presence of parasitic infections (e.g., Chagas disease due to Trypanosoma cruzi), therapy includes antiparasitic agents and management of cardiac complications.
Immune-mediated myocarditis: In cases with a clear autoimmune component (including eosinophilic or granulomatous forms), corticosteroids and other immunosuppressants (e.g., azathioprine) are used to reduce inflammation.
Toxic myocarditis: It is essential to discontinue the toxic agent (drugs, alcohol, drugs of abuse, or chemicals) and provide cardiac support to favor myocardial tissue recovery.
Idiopathic myocarditis: In the absence of an identifiable cause, treatment is mainly supportive; in some cases, immunomodulatory therapy may be considered if a latent autoimmune component is suspected.
Advanced Therapies
In patients with fulminant myocarditis or progression toward dilated cardiomyopathy, advanced therapies may be necessary:
Mechanical support: The use of ventricular assist devices in cases of cardiogenic shock.
Heart transplantation: Considered a last resort in cases of irreversible myocardial damage unresponsive to conventional treatment.
Prognosis
Prognosis in myocarditis is variable and depends on several factors, such as the extent of myocardial damage, timeliness of treatment, and specific etiology.
Favorable prognosis: In patients with mild forms and early treatment, cardiac function can recover completely.
Uncertain prognosis: Moderate myocarditis may progress to a chronic condition, with development of fibrosis and, in some cases, progression to dilated cardiomyopathy.
Poor prognosis: Fulminant forms, despite intensive treatment, may lead to cardiogenic shock and increased mortality.
Key prognostic factors include the extent of myocardial injury, initial response to therapy, presence of complications, and the interval between symptom onset and therapeutic intervention. Regular follow-up, with instrumental tests (such as echocardiography and CMR), is essential to monitor disease progression and adjust treatment.
References
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Mavrogeni et al. Role of cardiac magnetic resonance in myocarditis. Journal of Magnetic Resonance Imaging. 49(2), 2021, 352-364.
Friedrich et al. Pathophysiology and imaging in myocarditis. European Journal of Radiology. 46(3), 2021, 112-121.
Sagar et al. Viral myocarditis: Current perspectives. Nature Reviews Cardiology. 15(8), 2020, 453-470.
Imazio et al. Pericarditis and myocarditis: similarities and differences. Journal of the American College of Cardiology. 77(7), 2021, 799-812.
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