Myocarditis: Diagnosis and Treatment

When myocarditis is suspected, it is essential to follow a phased approach, starting with initial screening tests and progressing to advanced investigations to confirm the diagnosis and assess the severity and etiology of the condition.

Initial Phase (First Level)

In this phase, non-invasive and readily available tests are performed to provide preliminary indications of myocardial damage:

• Electrocardiogram (ECG): detects electrical abnormalities, rhythm alterations, and indirect signs of ischemia.
• Blood tests: assessment of biomarkers (troponin, CK-MB, BNP) and inflammatory markers (CRP, ESR) to indicate myocardial damage and inflammatory response.
• Chest X-ray: useful for identifying signs of heart failure and associated pulmonary abnormalities.
• Echocardiography: a first-line test that evaluates ventricular function, segmental motility, and detects effusions or signs of heart failure.

Confirmatory Diagnostic Phase (Second Level)

If initial data are suspicious, more advanced investigations are required for 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 enables histopathological diagnosis and analysis of inflammatory infiltrates according to the Dallas criteria.

Severity Assessment and Follow-Up Phase (Third Level)

Once myocarditis is confirmed, additional tests help define the extent of damage, severity of the disease, and guide treatment planning:

• Stress tests: performed during follow-up to evaluate the heart’s functional reserve and response to stress.
• Immunological and serological tests: aimed at identifying autoimmune markers or specific pathogens, useful in characterizing the etiology of myocarditis.

Integrating results from these phases allows for an accurate diagnosis, severity assessment, and determination of the origin of myocarditis, guiding therapeutic management and patient monitoring.

Treatment

The treatment of myocarditis varies based on etiology, severity, and the presence of complications. The therapeutic approach includes initial supportive therapy, specific treatment based on the cause, and in severe cases, advanced therapies.

Supportive Therapy

During the acute phase of myocarditis, when cardiac function is compromised, the focus is on supporting heart function and symptom control:

• Heart failure medications: ACE inhibitors, beta-blockers, and diuretics are used to improve ventricular function and reduce cardiac workload.
• Inotropic support: In patients with severe cardiac dysfunction, inotropic agents help sustain myocardial contractility.
• Arrhythmia management: Antiarrhythmics and, in selected cases, electrical cardioversion, to control heart rhythm disturbances.

In stable myocarditis cases without cardiac dysfunction, these therapies are not required.

Specific Therapy

Targeted treatment varies based on the etiology of myocarditis and can be classified as follows:

• Viral Myocarditis: Generally managed with supportive therapy, as no universally effective antiviral therapy exists; in selected cases, immunomodulators may be considered.
• Bacterial Myocarditis: Treated with targeted antibiotics, chosen based on the identified or suspected pathogen, along with supportive therapy for cardiac function and monitoring of infectious complications.
• Fungal Myocarditis: Although rare, it requires treatment with specific antifungal agents, particularly in immunocompromised patients, alongside careful hemodynamic support.
• Parasitic Myocarditis: In cases of parasitic infections (e.g., Chagas disease from Trypanosoma cruzi), treatment includes antiparasitic agents, along with 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, substances, or chemicals) and provide cardiac support to facilitate myocardial recovery.
• Idiopathic Myocarditis: In the absence of an identifiable cause, treatment is primarily supportive; in some cases, immunomodulatory therapy may be considered if an underlying autoimmune component is suspected.

Advanced Therapies

In patients with fulminant myocarditis or progression to dilated cardiomyopathy, advanced therapies may be necessary:

• Mechanical support: The use of ventricular assist devices in cases of cardiogenic shock.
• Heart transplant: Considered a last resort in cases of irreversible myocardial damage unresponsive to conventional treatment.

Prognosis

The prognosis of myocarditis is highly variable and depends on several factors, including the extent of myocardial damage, timeliness of treatment, and specific etiology.

• Favorable prognosis: In patients with mild forms treated early, cardiac function can fully recover.
• Uncertain prognosis: Moderate myocarditis may evolve into a chronic condition, with fibrosis development 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 damage, initial response to therapy, presence of complications, and the time elapsed between symptom onset and therapeutic intervention. Regular follow-up with instrumental examinations (such as echocardiography and CMR) is essential to monitor disease progression and adjust treatment accordingly.

References
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