Acquired Conduction Disease in Pediatric Myocarditis: A Review of the Literature and Case Series.

Myocarditis is an important cause of mortality, and particularly sudden death, in children. Arrhythmias, particularly tachyarrhythmias, are a known clinical sequelae of myocarditis. Bradyarrhythmias and conduction disease in pediatric myocarditis are a less common, but potentially critical complication of myocarditis, which may be associated with increased morbidity and mortality. Pediatric myocarditis with effects on atrioventricular conduction and ventricular conduction represents an underexplored and clinically significant field. We conducted a systematic review of the published literature and present two cases of significant conduction disease. Literature searches were performed as per PRISMA guidelines in Medline, EMBASE, Web of Science, and Cochrane Systematic Reviews. We analyzed 53 articles and identified 175 published cases of atrioventricular (AV) conduction disease and bradyarrhythmias in pediatric myocarditis. Diagnostic approaches were varied among the studies, with heterogeneity in both serum investigations, cardiac imaging, and management of the conduction issues. There were 91 cases of complete heart block, 53 cases of first-degree heart block, 11 cases of second-degree heart block, and 10 reported cases of clinically significant sinus bradycardia. Of the 175 reported cases, 31 required temporary pacing, with 10 having a pacemaker implanted, and the remaining were treated with medical therapy alone and did not require pacemaker placement. In this review, there were 13 deaths among the 175 reported cases, all of whom had complete heart block. AV conduction disease in pediatric myocarditis, although less common, can be clinically significant and have severe outcomes. The variation in presentation, treatment, outcome, and diversity in pathogens warrants further study in order to improve our understanding of this potential complication of myocarditis.