What is the management of myocarditis in the pediatric population?

Management of Myocarditis in Pediatric Population

All children with suspected myocarditis should be hospitalized immediately for cardiac monitoring and aggressive supportive care, with early consideration of mechanical circulatory support (ECMO) for fulminant cases, as this approach bridges the acute but often curable stage of disease and paradoxically leads to better long-term outcomes than non-fulminant presentations. 1, 2

Initial Assessment and Stabilization

Diagnostic Evaluation

• Perform immediate ECG, echocardiography, and cardiac biomarkers (troponin T, BNP/NT-proBNP) in all suspected cases to establish diagnosis and guide management 1, 3
• Consider viral testing including nasal swab, stool samples, and blood PCR to identify causative agents 4, 1
• Establish continuous ECG monitoring and invasive arterial line placement for hemodynamic monitoring in unstable patients 3
• Cardiac MRI with gadolinium contrast using the 2009 Lake Louise Criteria is indicated to confirm myocardial inflammation, differentiate ischemic from non-ischemic causes, and provide risk stratification 4

The Lake Louise Criteria demonstrate 82% sensitivity in pediatric myocarditis and should remain the diagnostic standard in centers experienced with their application 4. CMR shows characteristic subepicardial or patchy LGE enhancement (non-coronary distribution) distinguishing myocarditis from myocardial infarction 4.

Role of Endomyocardial Biopsy

• Consider EMB in patients who fail to recover clinically to guide targeted therapy, particularly for giant cell or eosinophilic myocarditis requiring immunomodulator therapy 4, 1
• EMB remains the gold standard but is reserved for cases requiring diagnostic clarification for specific treatment decisions 5, 6

Medical Management

Immunomodulatory Therapy

• Administer IVIG at 2 g/kg (based on ideal body weight) as first-tier immunomodulatory treatment 1
• Add low-to-moderate dose glucocorticoids (1-2 mg/kg/day) as adjunctive therapy with IVIG only in patients with shock and/or organ-threatening disease 1
• Do not use corticosteroids alone without IVIG, as this approach shows no benefit in pediatric myocarditis 4, 1

Despite widespread IVIG use (49% of hospitalized cases), a large multi-institutional study found no survival advantage even in the sickest patients 7. However, current guidelines continue to recommend IVIG based on safety profile and uncontrolled studies suggesting benefit 1, 8.

Heart Failure Management

• Implement guideline-directed heart failure therapy including diuretics, ACE inhibitors, and beta-blockers as appropriate 4, 1
• Start ACE inhibitors (e.g., captopril 1-6.25 mg) only if systolic blood pressure >100 mmHg 2
• Use beta-blockers only in hemodynamically stable patients; avoid in overt heart failure with pulmonary congestion or low output 2

Inotropic Support for Cardiogenic Shock

• Initiate individualized inotropic support with epinephrine, levosimendan, dopamine, or dobutamine based on hemodynamic response 3
• Start dopamine at 5 mcg/kg/min, increasing in 5-10 mcg/kg/min increments up to 20-50 mcg/kg/min; use caution at doses >7 mcg/kg/min due to increased pulmonary vascular resistance 2, 3
• Consider dobutamine 2-20 mcg/kg/min for myocardial dysfunction with adequate blood pressure 3
• Levosimendan shows improved ejection fraction and reduced catecholamine duration in small pediatric studies 3

Mechanical Circulatory Support

Indications for ECMO

Aggressive hemodynamic support using ECMO or percutaneous cardiopulmonary support is recommended for fulminant myocarditis to bridge the acute stage, with initiation indicated for:

• Cardiogenic shock not responding rapidly to pharmacological therapy 4, 2
• Refractory VT or VF not responding to 3-5 defibrillation attempts 4
• Pre-cardiac arrest state in acute fulminant myocarditis 4, 1, 3
• Cardiac index <2.2 L/min/m², cardiac power output <0.6 W, and elevated lactate despite initial therapy 3

Very low-quality evidence from 20 children suggests pre-cardiac arrest ECMO use may be beneficial in fulminant myocarditis 4. ECMO was required in 7% of hospitalized pediatric myocarditis cases 7.

Prognosis with Mechanical Support

The short-term survival rate for fulminant myocarditis is only 58% 4, 2. However, patients with fulminant myocarditis who survive the acute phase have paradoxically better long-term outcomes (93% alive without transplant at 11 years) compared to non-fulminant cases (45% at 11 years) 4, 2.

Arrhythmia Management

Ventricular Arrhythmias

• Ventricular tachycardia accounts for 76% of sustained arrhythmias in pediatric myocarditis 4
• Patients with sustained arrhythmias have 5.4-fold increased risk of cardiac arrest, need for mechanical support, or death (OR 5.4,95% CI 3.9-7.4) 4
• Initiate percutaneous cardiopulmonary support for refractory VT/VF after 3-5 failed defibrillation attempts 4

Conduction Abnormalities

• Obtain EKGs every 48 hours during hospitalization and at each follow-up visit 1
• Consider temporary pacing for symptomatic heart block or when serious VAs are triggered 4, 2
• Permanent pacemaker implantation may be needed if AV block persists, with device selection based on ventricular dysfunction prognosis 2

Advanced Therapies

Heart Transplantation

• Heart transplantation is recommended for children with severe end-stage heart failure from myocarditis refractory to medical and mechanical support 4, 1
• Transplantation was required in 5% of hospitalized pediatric myocarditis cases 7

ICD Consideration

• ICDs can be useful in high-risk patients with DCM to prevent sudden death, though specific pediatric myocarditis data are limited 4

Follow-Up and Monitoring

Serial Imaging

• Repeat echocardiograms at 7-14 days and 4-6 weeks after initial presentation 1
• Perform cardiac MRI at 2-6 months post-acute illness in patients with LV dysfunction to evaluate for fibrosis and scarring, as myocarditis has known association with dilated cardiomyopathy 4, 1

Ongoing Assessment

• Continue serial monitoring of inflammatory markers, BNP/NT-proBNP, and troponin T to guide treatment decisions 1
• Assess end-organ perfusion through clinical examination, urine output, and laboratory parameters 3
• Coordinate care across multiple specialists given the complex, multisystem nature of severe myocarditis 4, 1

Critical Pitfalls to Avoid

• Do not delay echocardiographic evaluation in suspected cases 3
• Do not rely solely on blood pressure without evaluating tissue perfusion markers 3
• Do not use corticosteroids as monotherapy without IVIG 4, 1
• Do not delay consideration of mechanical support in fulminant presentations, as early ECMO improves outcomes 4, 2
• Recognize that overall mortality is 8% in hospitalized pediatric myocarditis, with considerable resource utilization including mechanical ventilation (25%) and ECMO (7%) 7