Age-specific coronary outcomes in subacute Kawasaki disease.

BACKGROUND: Coronary artery (CA) lesions (CALs) are major complications of Kawasaki disease (KD). Studies have reported that coronary outcomes (CAL regression and progression) are associated with age; however, age-stratified data remain limited. METHODS: We analyzed data from 129,950 patients with KD in Japan (2011-2022). CALs were classified as CA dilatation, CA aneurysm, or giant CA aneurysm. Coronary outcomes were assessed by comparing echocardiographic findings between baseline and the subacute phase. Patients were stratified into nine 6-month age groups. Restricted cubic splines (RCS) were used to assess non-linear associations between age and coronary outcomes. Multivariable logistic regression analyses assessed age-specific associations using the RCS-identified reference group. RESULTS: Among patients without CALs at initial echocardiography, the 0-6-month group had the highest proportion with subsequent CAL development (2.8%). Among patients with CA dilatation, the 0-6-month group showed the lowest proportion of patients with CA regression (75.5%). RCS analyses identified the 25-30-month group as the most likely to show CA dilatation regression and the least likely to experience CAL progression. Multivariable analysis demonstrated that patients aged 0-6 months were significantly less likely to show CA dilatation regression (adjusted odds ratio [95% confidence interval]: 0.44 [0.30-0.63], reference: 25-30 months) and more likely to experience CAL progression (3.84 [3.03-4.86]). CONCLUSIONS: Coronary outcomes differed substantially across age groups; patients aged 0-6 months had the most adverse coronary outcomes. Even without CALs at initial echocardiography, this age group had the highest risk of subsequent CAL development.