Contemporary etiology, outcomes, and therapy in pediatric myocarditis

Myocarditis comprises a large proportion of pediatric cardiomyopathies. Viruses most commonly cause pediatric myocarditis but the diagnosed frequency of specific viruses that are responsible for pediatric myocarditis continues to evolve over time. A recent Pediatric Cardiomyopathy Registry (PCMR) analysis in the largest group of pediatric myocarditis patients ever studied confirmed that the most common outcome in pediatric myocarditis is cardiac recovery, but a substantial group of patients die or require heart transplantation after contracting the disease. A limited number of biomarkers associated both good (recovery) and poor (death or transplantation) outcomes could be identified. Immunosuppressive/immunomodulating therapy for pediatric myocarditis remains controversial with both proponents and adversaries. While small case series have shown benefit of these therapies in pediatric myocarditis, the high rate of spontaneous improvement with supportive care may make the definitive proof of efficacy in future clinical trials problematic. The effect of immune globulin on the outcome of pediatric myocarditis is uncertain. Myocarditis is the underlying disease leading to heart transplantation in a considerable number of children, but recent evidence from the PCMR and Pediatric Heart Transplant Study (PHTS) merged dataset suggests that their outcomes are poorer than for other cardiomyopathies after transplant. The increased availability of pediatric ventricular assist devices in North America may provide an opportunity to more effectively bridge critically ill myocarditis patients to transplantation and, more dramatically, to recovery.