Global epidemiology of myocarditis: disparities in age, sex and geography.

Myocarditis is a clinically and aetiologically heterogeneous disease that is associated with substantial morbidity and mortality, with approximately a million new cases and 17,000 deaths annually worldwide. However, the incidence of myocarditis varies widely by geographical region, sex and age. The aetiology of myocarditis is multifactorial and shaped by regional, demographic and socioeconomic contexts. In high-income countries, parvovirus B19 and human herpesvirus 6 are the predominant cardiotropic viruses that induce lymphocytic myocarditis, particularly in children. By contrast, in low-to-middle-income countries, dengue virus, human immunodeficiency virus, Plasmodium spp. (malaria) and Trypanosoma cruzi (Chagas disease) are the most common causative pathogens. Systemic autoimmune conditions and genetic predisposition are also implicated in the development of myocarditis, and increasingly recognized iatrogenic triggers of myocarditis include immune checkpoint inhibitors and gene therapies. This Review synthesizes epidemiological insights across diverse age groups and geographical regions, with a particular emphasis on the undiagnosed disease burden in low-resource settings. Variability in diagnostic criteria and the scarcity of heart-biopsy-confirmed data pose challenges to accurate estimates of global prevalence. Priorities for future research include multicentric registries, multi-omics-based risk stratification, and integration of novel biomarkers and advanced imaging techniques to refine myocarditis surveillance and treatment, and improve the accuracy of disease burden estimates.