Multisystem Inflammatory Syndrome in Children Requiring ECMO: Anticoagulation strategies and Lessons Learned

ABSTRACT

Intro Multisystem Inflammatory Syndrome in Children (MIS-C) is a post-infectious inflammatory response after exposure to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) which can cause acute cardiac dysfunction requiring mechanical circulatory support (MCS). MCS utilization for MIS-C is complicated by a propensity for thrombosis, which threatens circuit integrity. This study describes a cohort of MIS-C patients requiring MCS, their outcomes, and the anticoagulation strategies utilized. Method(s) A retrospective case series of patients diagnosed with MIS-C needing veno-arterial extracorporeal membrane oxygenation (VA-ECMO) at Children's Healthcare of Atlanta from March 1, 2020 to June 30, 2022. VA-ECMO variables, laboratory data, complications, and outcomes were collected. Result(s) Seven patients (all male) with severe MIS-C required VA-ECMO for acute cardiac dysfunction. Median age was 13 years (range 4-15 years). Median ICU stay was 13 days (range 6-17 days) with a median ECMO duration of 7 days (IQR 3-8 days) and median mechanical ventilation duration of 8 days (IQR 5-11 days). All seven patients survived to hospital discharge with good neurologic outcomes. Median time to qualitatively normal ventricular function by echocardiogram was 9.5 days (IQR 3-21 days). Heparin was initially used in 6 patients, bivalrudin initially used in 1 patient, and 1 patient converted from heparin to bivalirudin for refractory systemic thrombosis. Median heparin dose was 206u/kg/d (IQR 192-276u/kg/d) with median anti-Xa levels of 0.75 (IQR 0.1-1.1) and median daily PTT 102 seconds (IQR 83-107 seconds). Median daily PTT of patients receiving bivalirudin was 86 seconds (80-93 seconds). Median R-values by thromboelastography were 38 seconds (IQR 25-55 seconds). Two patients required catheter directed thrombolysis with tissue plasminogen activator (t-PA) for refractory intracardiac thrombi, both were initially started on heparin. Significant cannula thrombosis occurred in 2 patients, 1 initially started on heparin and 1 initially on bivalrudin. Bleeding resulting in compartment syndrome occurred in one patient on heparin requiring fasciotomy of the upper extremities, this patient was not receiving t-PA. Conclusion(s) Anticoagulation management for MIS-C patients requiring ECMO is fraught with challenges. A successful management strategy may necessitate higher heparin assay levels, the use of direct thrombin inhibitors for refractory thrombosis, and the deployment of catheter directed thrombolysis. In this case series, CDT was safely and successfully used in two patients. Further studies are required to understand the optimal anticoagulation strategy for these patients to minimize complications.