Fatal late cardiovascular sequelae of previously unrecognized Kawasaki disease in 12-year- old child

Background Kawasaki disease (KD), previously termed mucocutaneous lymph node syndrome, is a childhood vasculitis affecting medium-sized arteries and is the leading cause of acquired heart disease in children. It primarily affects children under five years of age. If left untreated, KD can lead to serious cardiovascular complications, particularly coronary artery aneurysms (CAA) and thrombosis. Incomplete KD presents with fewer clinical criteria, making it more difficult to diagnose. Importantly, long-term sequelae such as CAA may remain clinically silent for years. This case highlights the critical need for awareness that even minimal or transient symptoms can be the only warning sign of life-threatening complications in adolescents with a remote history of incomplete or unrecognized KD. Case presentation We describe a fatal case of a 12-year-old boy with a history of presumed myocarditis at age five, which retrospectively fulfilled criteria for incomplete KD but remained undiagnosed. From age five to twelve, he was asymptomatic except for occasional, brief chest tightness. At twelve, he presented with mild chest pain followed by rapid clinical deterioration, cardiac arrest, and death. Post-mortem imaging and autopsy revealed a thrombosed giant aneurysm of the left anterior descending coronary artery, consistent with chronic coronary disease. Conclusion This case illustrates the potentially fatal long-term cardiovascular sequelae of unrecognized and untreated incomplete KD. Early recognition and treatment with IVIG are critical to reduce coronary complications. Healthcare providers must maintain clinical vigilance for patients with a history of KD. Even subtle or transient symptoms in patients with a history of KD should prompt immediate evaluation to prevent fatal outcomes