BACKGROUND: Congenital heart disease (CHD) patients with pulmonary valve failure may undergo transcatheter pulmonary valve replacement (TPVR). Aspirin is often prescribed as long-term therapy after TPVR to prevent thromboembolic events (TE). AIMS: We aimed to examine the prevalence of aspirin resistance within the CHD TPVR population. METHODS: The VerifyNow point-of-care test quantifies platelet aggregation as Aspirin Reactivity Units (ARU). ARU values greater than 550 suggest aspirin resistance (AR). A retrospective chart review analyzed ARU test results from May 2022 through December 2023 in CHD patients following successful TPVR (n = 48). Lifelong TE history was collected. Association between AR and sex, race, and ethnicity was examined with Fisher's Exact test, and the Wilcoxon rank sum exact test analyzed associations between AR and age. RESULTS: Three of 45 (6.67%) CHD TPVR aspirin-compliant patients (average age 33.14 years
range 0.74-77.86 years, 47% females) were AR. Interestingly, all AR patients were females, suggesting higher AR prevalence in females (p = 0.094). No significant associations were found between AR and age (p = 0.8), race (p = 0.077), or ethnicity (p = 0.2). No AR patients had a documented history of TE. Five of 42 (11.9%) aspirin sensitive patients had TE while taking aspirin, including two females (not on birth control at time of event) and three males. CONCLUSIONS: AR is prevalent in CHD TPVR patients, but TE occurrence did not correlate with AR. However, AR exclusively in females and TE in aspirin sensitive patients, suggests need for further investigations on the most effective TE prophylaxis in this population.