Rivaroxaban Versus Warfarin for Thromboprophylaxis in Children With Giant Coronary Aneurysms After Kawasaki Disease

Inclusion Criteria: Children aged 1 Month to <18 years with confirmed giant coronary aneurysm(s) in any coronary artery during acute or cardiac sequelae phase of Kawasaki disease. Giant coronary aneurysm(s) should confirmed by diagnostic imaging examination and meet the diagnostic criteria of Z-score ≥10 or coronary artery internal lumen diameter ≥8mm. Current anticoagulation therapy is long-term oral Warfarin treatment with stable INR. INR monitoring has reached the target range (1.5-2.5) for two consecutive times in the past month, with each examination interval of at least one week Participant should be able to tolerate oral/nasogastric/gastric feeding and require antithrombotic drug therapy for at least 1 year. For children with history of severe occlusion of coronary artery and performed coronary artery bypass grafting, percutaneous coronary intervention or thrombolytic therapy: At least 1 week after medical intervention Clinically stable Body weight ≥ 2600g Informed consent from parents or legal guardians provided. If children aged ≥ 10 years, informed consent from children is required. Exclusion Criteria: Active bleeding or bleeding risk contraindicating anticoagulant therapy With history of venous thromboembolism or risk factors related with venous thromboembolism, like congenital heart disease, carcinoma, central venous catheter or long-term immobilization. Thrombus within giant coronary aneurysm was confirmed by previous imaging examinations, including echocardiography, computed tomography angiography in coronary artery or coronary angiography An estimated glomerular filtration rate (eGFR) <30mL/min/1.73 m2 (in children younger than 1 year, serum creatinine results above 97.5th percentile excludes participation) Platelet count < 50 x 109/L Hepatic disease which is associated w ith either: coagulopathy leading to a clinically relevant bleeding risk, or alanine aminotransferase (ALT)> 5x upper level of normal (ULN) or total bilirubin (TB)> 2x ULN with direct bilirubin > 20% of the total Sustained uncontrolled hypertension defined as systolic and/or diastolic blood pressure >95 th age percentile Concomitant use of strong inhibitors of both cytochrome P450 isoenzyme 3A4 (CYP3A4) and P-glycoprotein (P-gp),including but not limited to all human immunodeficiency virus protease inhibitors and the following azole-antimycotics agents: ketoconazole, itraconazole, voriconazole, posaconazole, if used systemically (fluconazole is allowed) Concomitant use of strong inducers of CYP3A4, including but not limited to rifampicin, rifabutin, phenobarbital, phenytoin and carbamazepine Childbearing potential without proper contraceptive measures, pregnancy or breast feeding Life expectancy <3 Month Hypersensitivity or any other contraindication listed in the local labeling for the comparator treatment or experimental treatment Inability to cooperate with the study procedures Participation in a study with an investigational drug or medical device within 30 days prior to randomization