Midterm cardiovascular outcomes in children with MIS-C compared to Kawasaki disease: a multicenter prospective cohort study.

The overlapping features of multisystem inflammatory syndrome in children (MIS-C) and Kawasaki disease (KD) raise concerns regarding midterm cardiovascular sequelae. We conducted a multicenter prospective cohort study to compare midterm outcomes in MIS-C and KD survivors. A total of 122 children (MIS-C, n = 66; KD, n = 56) underwent echocardiographic follow-up 1-3 years post-diagnosis. Outcomes included left ventricular ejection fraction (LVEF), coronary abnormalities, and left ventricular global longitudinal strain (LVGLS). Notably, the median age at diagnosis was higher in MIS-C (5.7 years, IQR 3.0-9.4) than in KD (1.5 years, IQR 1.1-2.8) (P < 0.01). Initial left ventricular dysfunction occurred more frequently in MIS-C (25.8%) than KD (0%) (P < 0.01). By the median follow-up of 1.5 years (IQR 1.1-1.9), all patients who had previously been diagnosed with left ventricular dysfunction had recovered to normal LVEF in both groups. However, one MIS-C patient had persistently abnormal LVGLS, suggesting subclinical impairment. Coronary abnormalities in MIS-C decreased from 30% at baseline to 1.5% at follow-up. In contrast, persistent coronary abnormalities remained in KD, despite preserved cardiac function and LVGLS. At follow-up, coronary abnormalities including coronary ectasia and aneurysm were significantly higher in KD (14.2%) compared with MIS-C (1.5%) (P < 0.01). In conclusion, MIS-C was associated with transient ventricular dysfunction but rare persistent coronary involvement, whereas KD carried a higher burden of midterm coronary abnormalities. Clinical trial registration: TCTR20230414003.