Thromboembolic complications are an important source of morbidity in children with congenital and acquired heart disease. Management is challenging because haemostasis characteristics evolve with age, evidence is limited and clinical scenarios are heterogeneous.

To provide practical expert consensus recommendations on thromboprophylaxis in congenital and acquired heart disease from infancy to adolescence.

A multidisciplinary expert panel from the Paediatric and Congenital Cardiology Branch of the French Society of Cardiology conducted a focused literature review and structured consensus process. Recommendations were graded pragmatically according to available evidence and expert agreement.

During infancy and childhood, thrombosis risk is increased in selected conditions, such as Kawasaki disease, paediatric cardiomyopathy and procedural neonatal exposure. During adolescence, bleeding risk may rise, particularly in girls, because of dysovulation and abnormal uterine bleeding during antithrombotic therapy. Across all stages, management should rely on individualized treatment, integrating thrombosis-bleeding balance, serial assessment, patient education and selection between antiplatelet therapy, vitamin K antagonists and direct oral anticoagulants according to indication and age. Aspirin therapy remains the first choice in several indications, whereas anticoagulation is required in selected high-risk conditions. Direct oral anticoagulants are emerging as promising alternatives in older children, although paediatric-specific data remain limited.

Thromboprophylaxis from infancy to adolescence requires individualized age-specific and dynamic strategies that account for changing haemostatic profiles, cardiac anatomy, procedural exposure and sex-specific bleeding risks. Prospective paediatric studies are needed to optimize treatment selection and duration.