Aspirin Responsiveness in a Cohort of Paediatric Patients With Bovine Jugular Venous Valves and Right Ventricle to Pulmonary Artery Conduits

Abstract Objective: The aim of this study was to determine the rate of aspirin responsiveness in a cohort of paediatric patients with in-situ xenograft valved right ventricle to pulmonary artery (RV-PA) conduits and/or bovine jugular venous valves (BJV). Aspirin is routinely prescribed to these patients. Optimising anti-platelet therapy could promote valve longevity and reduce the risk of infective endocarditis in this at-risk group. Materials and Methods: This was a prospective, observational study. Patients were recruited from both ward and outpatient settings. Patients were eligible if under 18 years and taking aspirin. Non-response to aspirin was defined as >20% platelet aggregation using light-transmission platelet aggregometry (LTA) and <50% platelet inhibition by thromboelastography with platelet mapping (TEGPM). Participants were invited to provide a confirmatory sample in cases of aspirin resistance and dose adjustments were made. Results: Thirty patients participated. Median age was 9 years (2 months – 18 years). The majority (93%) had complex right ventricular outflow tract pathology. 13 (43%) had an RV-PA conduit, 24 (80%) had a BJV, with valve situated in conduit in 7 (23%) cases. Rate of aspirin non-response on initial testing was 23% (n=7/30) with median LTA 25.45% (24.9-40%) and TEG 13.25% (0-44%) in non-responders. Non-responders were more likely to be under 1 year. Two patients required dose increases and one patient non-adherence to dose was identified. In 4 patients repeat testing revealed normal results. Conclusions The rate of aspirin non-response on laboratory testing in this cohort of patients was 23% and resulted in therapeutic intervention in 10%.