Aspirin Responsiveness in a Cohort of Pediatric Patients with Right Ventricle to Pulmonary Artery Conduits and Transcatheter Valve Replacement Systems

Abstract

The aim of this study was to determine the rate of aspirin responsiveness in a cohort of pediatric patients with in situ xenograft valved right ventricle to pulmonary artery (RV-PA) conduits and/or transcatheter valve replacements (TVR). Aspirin is routinely prescribed to these patients. Optimizing anti-platelet therapy could promote valve longevity and reduce the risk of infective endocarditis in this at-risk group. 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. Thirty patients participated. Median age was 9 years (2 months to 18 years). The majority (93%) had complex right ventricular outflow tract pathology. 13 (43%) had an RV-PA conduit and 24 (80%) had a TVR, 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 74.55% (60–76%) 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. Four patients on repeat testing were responsive to aspirin by laboratory tests. The rate of aspirin non-response on laboratory testing in this cohort of patients was 23% and resulted in therapeutic intervention in 10%.

The Effects of Aspirin dose in Children with Congenital and Acquired Heart Disease. Results from the Paediatric Study of Aspirin Efficacy using Diagnostic and Monitoring Tools (PAED-M)

“…Habib et al reported that aspirin thromboprophylaxis before the onset of cardiovascular implantable electronic device-related bloodstream infection was associated with a lower likelihood of vegetation formation on the device [23] and in a similar manner, Eisen et al concluded that aspirin usage was associated with a reduced risk of emergency valve replacement surgery in patients with Staphylococcus aureus-associated infective endocarditis [25]. As a result of the high prevalence of reduced response to aspirin in this sub-cohort, patients with RV-PA conduits were followed up in a subsequent institutional study [26]. Three patients (12.5%) in Q1 and Q2 (n = 3/24) had suboptimum responses to aspirin had Fontan conduits.…”

“…A proposed algorithm for testing is outlined in Fig. 3, adapted from our earlier study [26]. There has been much debate on the relationship between aspirin dose and treatment effect, particularly in adult populations [32,33] but more recently in pediatric patients [7,8].…”

“…Fig. 3 Proposed aspirin responsiveness testing algorithm [26] Funding Open Access funding provided by the IReL Consortium. This study was supported by an institutional grant as part of a Clinical Research Fellowship for IER from the National Children's Research Center, Ireland.…”