Abstract Number: LBA21 Platelet Function Assays for Aspirin and Ticagrelor are More Reliable When Compared with Clopidogrel

Abstract

Introduction The most common antiplatelet agents administered for neurovascular disease treatment and prevention are aspirin, clopidogrel, and ticagrelor. The utility of monitoring various platelet function assays (PFAs) in relation to neurovascular disease is unclear and variability exists in clinical practice. The aim of this study was to evaluate reliability of PFAs as a biomarker of the platelet inhibition in aspirin, clopidogrel, and ticagrelor in patients on antiplatelet agents for a broad range of neurovascular indications. Methods We conducted a retrospective chart review of prospectively collected data on patients who presented to our comprehensive stroke center and had PFAs drawn. PFAs utilized include Aspirin VerifyNow test, measured in aspirin resistance units (ARU) and Plavix VerifyNow test, measured in P2Y12 reaction units (PRU). Values less than 550 ARU are consistent with aspirin‐induced platelet inhibition. Similarly, values less than 197 PRU are indicative of platelet inhibition in clopidogrel or ticagrelor. Compliance and incidence of intracranial hemorrhage (ICH) and other adverse bleeding events were assessed. Social science statistics software was used for data analysis. Results From January to June 2022, a total of 297 patients had platelet function assays drawn for neurovascular indications. Average age was 69.96 (95% CI 68.31, 71.61). One hundred and eighty nine subjects were on aspirin. Mean ARU was 448.73 (95% CI 438.53, 458.93). One hundred twenty three subjects were on clopidogrel. Mean PRU for clopidogrel was 162.84 (95% CI 147.33, 178.35). Fifteen subjects were on ticagrelor. Mean PRU for ticagrelor was 73.27 (95% CI 34.62, 111.91). There was a significant difference in therapeutic platelet inhibition between clopidogrel and ticagrelor in subjects who were compliant (n = 105 clopidogrel complaint; n = 14 ticagrelor complaint) (z‐score 3.63, p‐value 0.00028). Of the patients that were compliant none had a non therapeutic platelet inhibition on aspirin and ticagrelor. Of the 123 patients that were compliant on clopidogrel 76% had non therapeutic PFA (n = 8 clopidogrel and ICH; n = 1 ticagrelor and ICH) (Fisher value = 0.0205). Conclusions Our study suggests that platelet inhibition of aspirin and ticagrelor may be more reliable when compared to that of clopidogrel. Significant limitations include the discrepancy in respective sample sizes. Larger studies are needed to validate our results.