Frequency, characteristics, antithrombotic therapies, and outcomes of thromboembolism in paediatric patients with CHD undergoing cardiac surgery: a single centre retrospective study.

Introduction: Thromboembolism is a complication in paediatric patients with CHD requiring cardiac surgery. Previous research has focused on post-operative thromboembolism. This study aimed to describe thromboembolism frequency before or after cardiac surgery in children with CHD.

Methods: We performed a single-centre retrospective study from October 2020 to June 2023 (inclusive). Patients were eligible for inclusion if they were <21 years of age and underwent cardiac surgery. Outcomes of interest included the occurrence and characteristics of thromboembolism in the 12 months before and after surgery, antithrombotic therapies, recurrent thromboembolism, and clinically significant bleeding.

Results: Among 260 patients included, 35 (13.5%) developed an index thromboembolism. Twelve (34.3%) patients had an index thromboembolism <12 months before surgery and 23 (65.7%) had an index thromboembolism <12 months after surgery, including 8 (22.9%) patients who had thromboembolism during both exposure periods. The median interquartile range (IQR) time of thromboembolism relative to cardiac surgery was -26 (-4 to -140) days and 15 (4 to 41) days, respectively. Seven (20%) patients had arterial, 18 (51.4%) venous, and 3 (8.6%) had both arterial and venous thromboembolism. Median (IQR) antithrombotic therapy duration was 49 (24-84) days. Nine (25.7%) patients developed recurrent thromboembolism and five (14.3%) patients experienced clinically significant bleeding.

Conclusions: The risk of thromboembolism and recurrence is high both before and after cardiac surgery among paediatric patients with CHD. Prospective multi-centre studies should seek to identify risk factors for preoperative and postoperative thromboembolism to inform the design of future risk-stratified thromboembolism prevention trials in children with CHD.