Anticoagulation and Thrombotic Events in the Multisystem Inflammatory Syndrome in Children: Experience of a Single-center Cohort and Review of the Literature

The multisystem inflammatory syndrome in children (MIS-C) is a severe clinical entity affecting the coagulative system; although thromboembolic events (TEs) are not common, most patients receive anticoagulation. We retrospectively assessed patients below 18 years admitted with MIS-C at Meyer Children's Hospital (Florence, Italy). Data on baseline clinical and laboratory presentation, treatment, and outcome, including differences between patients with and without thrombotic prophylaxis, were analyzed. Thirty-two children 1 to 15 years were included. Seventeen patients (53.1%) required intensive care admission, 2 (8.7%) had obesity, 7 (30.4%) had a central venous catheter, and 14 (43.8%) impaired cardiac function. Twelve patients (37.5%) received prophylactic anticoagulation: they had more frequent cardiac involvement (91.7 vs. 50%, P=0.02) and higher ferritin levels (median 1240 vs. 501.5 ng/mL, P<0.001). No differences were found in median d-dimers between the 2 groups. Twenty-one patients (65.6%) had d-dimers >5×upper limit of normal but the indication for anticoagulation was not driven by d-dimers. No patient had hemorrhagic events and only 1 patient (3.1%) had a superficial thrombotic event (under thromboprophylaxis). Our series and the available literature data on MIS-C and thromboembolic events suggest that TEs are a rare complication of MIS-C that is frequently associated with high d-dimer values. However, also in MIS-C, the well-established risk factors of pediatric TEs (ie, older age, central venous catheter, obesity, and cancer) should guide thromboembolic risk assessment.