Our suggested approach to antithrombotic therapy in hospitalized patients with multisystem inflammatory syndrome in children

MIS-C: multisystem inflammatory syndrome in children; VTE: venous thromboembolism; LV: left ventricular; CA: coronary artery; LMWH: low molecular weight heparin; COVID-19: coronavirus disease 2019.
* All patients who meet diagnostic criteria for MIS-C are treated with low-dose aspirin (3 to 5 mg/kg) unless they have a contraindication. This is extrapolated from the practice of using aspirin in the management of children with Kawasaki disease.
¶ Indications for therapeutic anticoagulation in this setting are not standardized, and practice varies considerably. In addition to the circumstances listed above, some experts would also administer therapeutic anticoagulation to patients with severe manifestations of MIS-C if the D-dimer is markedly elevated (ie, >10 times the upper limit of normal).
Δ Refer to UpToDate topics and drug information monographs for suggested therapeutic and prophylactic dosing of LMWH.
◊ In patients without an indication for therapeutic anticoagulation and who are not critically ill, the decision to provide pharmacologic VTE prophylaxis is individualized, weighing the risk of thrombosis and risk of bleeding. The diagnosis of COVID-19-related MIS-C itself should be considered a major risk factor for VTE. Other important risk factors include the presence of a central venous catheter, underlying malignancy, prolonged immobility, obesity, and oral contraceptives. VTE prophylaxis is appropriate for most adolescents hospitalized with MIS-C, provided that bleeding risk is not high. In younger children, the decision is made on a case-by-case basis. When VTE prophylaxis is used, LMWH is generally the preferred agent. Nonpharmacologic strategies for VTE prophylaxis (eg, intermittent pneumatic compression devices [size permitting] and early mobilization) are encouraged, but MIS-C-related hypercoagulability may merit a higher level of intervention. For details regarding other risk factors for VTE, refer to additional UpToDate content on VTE prophylaxis in children.