To determine the prevalence of subsequent stenotic lesions based on the maximum diameter of the largest coronary artery aneurysm in patients with Kawasaki disease and the threshold value of coronary artery diameter associated with risk of developing stenotic lesion.

There were 214 patients (160 males) who had at least 1 aneurysm in a selective coronary angiogram (CAG) done <100 days after the onset of Kawasaki disease were studied. We measured the maximal coronary artery aneurysm diameter in 3 major branches in the initial CAGs. Branches were classified into 3 groups according to their maximal coronary artery aneurysm diameter: large, ≥8.0 mm; medium, ≥6.0 mm but <8.0 mm; and small, <6.0 mm. Subsequent CAGs were performed in the late follow-up period. We investigated the stenotic lesion in the follow-up CAGs, and evaluated the prevalence of stenotic lesion in each group based on body surface area (BSA) by the Kaplan-Meier method. Localized stenosis of ≥25% and complete occlusion were included as stenotic lesion in this study. We also determined the cutoff point for stenotic lesion.

The median interval from the initial CAGs to the latest CAG was 8 years, with a maximum of 32 years. For a BSA of <0.50 m², the 20-year prevalence of large and medium stenotic lesions was 78% (n = 62; 95% CI, 63-89) and 81% (n = 40; 95% CI, 63-89), respectively. For a BSA of ≥0.50 m², large and medium stenotic lesions were 82% (n = 75; 95% CI, 67-91) and 40% (n = 56; 95% CI, 20-64), respectively (P < .0001).

The cutoff points of the coronary artery diameter within the first 100 days after the onset of Kawasaki disease leading to a stenotic lesion in the late period, were a diameter of ≥6.1 mm with a BSA of <0.50 m² and a diameter of ≥8.0 mm with a BSA of ≥0.50 m². Those cutoff points would have corresponded with a Z score of at least 10 on 2-dimensional echocardiography. Careful follow-up and antithrombotic therapy should be provided to patients who meet these criteria.