Did the COVID-19 pandemic change the Kawasaki disease phenotype? Observations from the International Kawasaki Disease Registry.

We sought to determine if the COVID-19 pandemic was associated with changes in Kawasaki disease (KD) phenotype and cardiac manifestations. Patients hospitalized with acute KD and enrolled into the International KD Registry were categorized into time periods based on admission date: during the pandemic (January 1, 2020 - September 30, 2022, 33 months) and after the pandemic (October 1, 2022 - September 30, 2025, 36 months). Only patients with verified KD diagnoses as per American Heart Association criteria with no evidence of preceding COVID-19 exposure were included. Demographics, clinical features, management, and cardiac manifestations were compared between time periods. From across 45 sites, 726 during pandemic and 813 after pandemic KD patients were included. During pandemic patients were younger (median 2.6 vs. 3.3 years; p < 0.001), more commonly had incomplete KD (15 vs. 9%; p < 0.001), were less likely to have cough (34 vs. 43%; p < 0.001) and sore throat (15 vs. 22%; p < 0.001), and there were no significant differences in immunomodulatory treatments received. Left ventricular ejection fraction was normal and maximal coronary artery Z scores (median, interquartile range 25-75%, 1.38 [0.77, 2.30] vs. 1.41[0.42, 2.37]; p = 0.08) were similar, including coronary artery aneurysm Z score categories. During the pandemic, KD patients were younger, more likely to present as incomplete KD, and less likely to have respiratory symptoms, with no differences in immunomodulatory treatments received. Cardiac manifestations were however similar. These findings suggest that the COVID-19 pandemic had minimal impact on KD phenotype especially cardiac manifestations.