In Japan, a 51-year-old man had minimally symptomatic severe acute respiratory syndrome coronavirus 2 infection. Multisystem inflammatory syndrome was diagnosed ≈5 weeks later; characteristics included severe inflammation, cardiac dysfunction, and IgG positivity. Clinicians should obtain detailed history and examine IgG levels for cases of inflammatory disease with unexplained cardiac decompensation.
Keywords: COVID-19; Japan; SARS-CoV-2; coronavirus disease; multisystem inflammatory syndrome; respiratory infections; severe acute respiratory syndrome coronavirus 2; viruses; zoonoses.