Treatment and Outcomes of Kawasaki Disease Over 40 Years

BACKGROUND: Kawasaki disease (KD) is the leading cause of acquired heart disease in children in developed countries. Long-term prognosis depends on coronary sequelae, yet Western longitudinal data integrating acute-phase features, treatment, and long-term coronary outcomes remain limited. METHODS: We conducted a longitudinal observational cohort study including consecutive children diagnosed with KD between 1982 and 2025 at a single tertiary pediatric referral center in Italy. All patients underwent clinical and echocardiographic assessment during the acute phase, followed by longitudinal annual follow-up. Coronary involvement (dilation or aneurysm) was assessed by echocardiography. RESULTS: Among 533 children (median age, 26 months; 59.8% male), 117 (22.0%) developed acute coronary involvement, including 27 aneurysms and 90 dilation. Intravenous immunoglobulin (IVIG) use increased from 53.3% in the 1980s to 99% after 2020. The highest rates of IVIG resistance (30.0%) and coronary lesions (27.2%) occurred between 2011 and 2020, followed by a decline in 2021-2025. Persistent coronary abnormalities were observed exclusively in patients with medium-giant aneurysms. Independent predictors of aneurysm were age less than 6 months (odds ratio [OR], 7.64), IVIG resistance (OR, 9.89), IVIG administration after day 10 (OR, 5.27), and pericardial effusion (OR, 3.16). No persistent coronary sequelae were observed in high-risk patients treated with interleukin-1 inhibitors. CONCLUSIONS: In this 40-year Italian cohort, coronary aneurysms were uncommon but exclusively determined long-term coronary sequelae. Younger age, delayed treatment or IVIG resistance, and pericardial effusion independently predicted aneurysm formation, highlighting major and potentially modifiable gaps in care delivery. These findings support specialist, risk-based management with prompt escalation to reduce long-term coronary morbidity.