This study aims to investigate the clinical phenotypes, management approaches, and outcomes of myocarditis in children admitted to Assiut University Children's Hospital. Myocarditis is an inflammatory disease of the heart muscle that can present in different clinical forms, including acute, fulminant, chronic active, and chronic persistent types. These forms vary in severity, treatment needs, and long-term outcomes.

Children aged 1-18 years who are diagnosed with myocarditis based on clinical findings, cardiac biomarkers, echocardiography, and electrocardiography (with MRI when available) will be included. Patients with congenital heart disease or cardiomyopathy unrelated to myocarditis will be excluded.

The study will follow eligible patients prospectively over a 12-month period. Detailed clinical assessment, laboratory tests, echocardiographic findings, and management strategies will be recorded. Special attention will be given to the role of corticosteroids and intravenous immunoglobulin (IVIG) in treatment. Outcomes including recovery of cardiac function, need for intensive care, and survival will be assessed.

By analyzing the clinical presentation, treatment, and prognosis of different myocarditis phenotypes, this study aims to improve the understanding of disease patterns in children and provide evidence to guide future management.

Myocarditis is an inflammatory disorder of the myocardium that may cause myocyte injury, necrosis, and cardiac dysfunction. Pediatric myocarditis has heterogeneous clinical phenotypes, commonly categorized into acute, fulminant, chronic active, and chronic persistent forms. These categories differ in pathophysiology, clinical presentation, and prognosis, making phenotypic classification essential for guiding treatment decisions and predicting outcomes.

In children, acute myocarditis often follows viral infection and may manifest with fever, chest pain, palpitations, or signs of heart failure. Fulminant myocarditis presents abruptly with severe hemodynamic compromise and cardiogenic shock, requiring intensive care and often mechanical circulatory support. Chronic active myocarditis is associated with ongoing inflammation, progressive ventricular dysfunction, and increased risk of dilated cardiomyopathy. Chronic persistent myocarditis may present with milder, prolonged symptoms but can still result in long-term morbidity.

This prospective cohort study will be conducted at Assiut University Children's Hospital over 12 months. Approximately 30 eligible pediatric patients will be enrolled using consecutive sampling. Inclusion criteria include children aged 1-18 years with clinically and diagnostically confirmed myocarditis. Exclusion criteria include congenital heart disease or cardiomyopathy unrelated to myocarditis.

All participants will undergo comprehensive evaluation including:

Clinical assessment: demographic data, presenting symptoms, signs of cardiac dysfunction, and general/systemic examination.

Laboratory tests: cardiac biomarkers (troponin, CK-MB), inflammatory markers (CRP, ESR), renal and liver function, lactate, and ABG.

Echocardiography: left ventricular dimensions, fractional shortening, ejection fraction, wall motion abnormalities, pericardial effusion, and valve regurgitation.

Electrocardiography and chest X-ray.

Management recording: medical therapy including corticosteroids, IVIG, inotropes, and supportive care.

Primary outcomes: classification of myocarditis phenotypes and assessment of treatment effectiveness, with focus on corticosteroids and IVIG.

Secondary outcomes: clinical improvement, recovery of cardiac function, survival, and requirement of intensive care or mechanical circulatory support.

Statistical analysis will be performed using SPSS. Data will be analyzed using descriptive and analytical methods, including Chi-square, t-tests, correlation, and regression analyses, with significance set at p < 0.05.

This study will contribute to understanding the spectrum of pediatric myocarditis in a tertiary care setting in Upper Egypt and provide insight into prognostic indicators and therapeutic strategies.

Inclusion Criteria:

• • Children aged between 1 to 18 years.

  • Children diagnosed with myocarditis based on clinical presentation, echocardiography, and cardiac biomarkers, ECG and MRI (if available)

Exclusion Criteria:

• • Children with congenital heart disease.

  • Known cardiomyopathy unrelated to myocarditis.

All available patients diagnosed with myocarditis and attending Assiut University children hospital during the study period will be included in this study All patients included in the study will have fulfilled the established criteria to ensure the appropriateness and consistency of the study population.