Comparison of rivaroxaban with warfarin for intracardiac thrombosis in the pediatric population at different cardiac sites: Early experience of anticoagulation approach and treatment outcomes

Aims: To compare the rivaroxaban treatment with warfarin for intracardiac thrombi resolution in pediatric patients diagnosed with intracardiac thrombosis (ICT). Methods: In 2020–24, we enrolled 18 [0.7 (0.3–12, Q1-Q3) years-old, 67 % males] consecutive ICT pediatric patients (< 16 years old) treated in 2020–22 with warfarin (n = 9, 0.1 mg/Kg/day) and in 2023–24 with rivaroxaban (n = 9, dosage based on patient's body weight). ICT was suspected by echocardiography and confirmed with cardiac computed tomography (CCT) or magnetic resonance (CMR) imaging. All the participants were treated with enoxaparin for 7 days before the rivaroxaban implementation. CCT/CMR was repeated to confirm ICT resolution. N = 9/18 (50 %) patients presented with right atrial thrombosis, n = 5/18 (28 %) and n = 3/18 (17 %) with right/left ventricular thrombi, respectively, and n = 1/18 (5 %) with left atrial appendage thrombus. Results: Compared with warfarin, treatment with rivaroxaban had a shorter duration (Log-rank P = 0.020); warfarin vs. rivaroxaban: 9.67 ± 3.6 vs. 6.6 ± 2.2 weeks (P = 0.0040). After rivaroxaban, all the thromboses were resolved and confirmed at the CCT/CMR imaging; no major bleeding event was documented during the treatment based on the BASIC bleeding assessment scale. Only minor bleedings were documented. In details: warfarin experienced n = 6/9 (67 %) gastrointestinal bleedings and n = 2/9 macroscopic hematuria, while 3 gingival bleedings were documented in the rivaroxaban group. After a follow-up period of 6 months, no recurrences were detected/suspected at the echocardiography evaluation. Conclusions: Among pediatric patients with ICT, irrespective of the thrombosis site, rivaroxaban seemed effective in thrombus resolution. ClinicalTrials.gov ID: NCT06371170