Prepared by Paul St. Laurent, DNP, RN, Sr. Science and Medicine Advisor, Lead
- Efforts to define myocarditis have evolved from historically relying on biopsy proven pathologic diagnosis to increasing use of cardiac magnetic resonance (CMR) imaging while continuing to integrate clinical and laboratory criteria to improve the diagnostic yield of these tools.
- This statement recognizes four strata that can confirm the diagnosis: (1) biopsy proven, (2) CMR confirmed clinically suspected, (3) clinically suspected, and (4) possible myocarditis.
- Study of the pathogenesis of myocarditis using animal models demonstrate an involvement of the activation of the inflammatory, innate, and adaptive immune responses. Autoimmunity has also been observed. Each response can be pathologic leading to myocyte injury.
- Acute myocarditis from a viral etiology is most prevalent in children; however, there remains a diverse array of infectious and non-infectious causes of myocarditis that should be considered in the differential diagnosis.
- The presentation can range from acute to chronic, and children presenting with acute heart failure can have life threatening ventricular arrhythmias or progress rapidly to cardiogenic shock.
- Direct tissue examination remains the gold-standard for proving the presence of myocarditis; however, advances in CMR have evolved as a valuable adjunct. CMR can demonstrate markers of inflammation and necrosis that characterize myocarditis histologically, but it is important to synthesize imaging and clinical information, including chronicity, to differentiate myopathic from inflammatory changes.
- Anticipatory care is important and includes careful triaging and admission to a ward that can monitor the cardiovascular condition closely, or transfer of the patient to a center that can provide advanced pediatric cardiovascular care including diagnostics, mechanical circulatory support, and transplantation.
- Immunotherapy, predominantly steroids and intravenous immunoglobulin, are commonly used despite the lack of evidence supporting their efficacy individually or when combined.
- Familiarity with the increasing adult literature—including CMR, intervention, exercise restrictions, and molecular genetic data—can help fill the gap of knowledge in the smaller pediatric population. For example, current guidelines recommend that Holter monitoring and exercise stress testing should be considered in athletes and that return to athletic competition should not occur sooner than 3-6 months.
- To improve outcomes, a set of criteria for the diagnosis of myocarditis based on current diagnostic tools should be top priority and will inform multi-institutional, scientifically rigorous investigation of current treatment options.
Law YM, Lal AK, Chen S, Čiháková D, Cooper LT Jr, Deshpande S, Godown J, Grosse-Wortmann L, Robinson JD, Towbin JA; on behalf of the American Heart Association Pediatric Heart Failure and Transplantation Committee of the Council on Lifelong Congenital Heart Disease and Heart Health in the Young and Stroke Council. Diagnosis and management of myocarditis in children: a scientific statement from the American Heart Association [published online ahead of print July 7, 2021]. Circulation. doi: 10.1161/CIR.0000000000001001