ABSTRACT NUMBER: ESOC2026A1047 PREDICTIVE MODELING OF PLATELET REACTIVITY DURING CLOPIDOGREL TAPERING IN ENDOVASCULAR TREATMENT OF ASYMPTOMATIC CEREBRAL ANEURYSMS: THE DOSIS MODEL

Abstract Background and aims Patients undergoing endovascular treatment with flow diverters for intracranial aneurysms require antiplatelet therapy. In hyper-responders, clopidogrel tapering are frequently employed. This study aimed to characterize the evolution of platelet reactivity, measured by P2Y12 Reaction Units (PRU), and to develop a predictive tool to identify patients at risk of loss of therapeutic platelet inhibition (PRU > 230) during maintenance. Methods Longitudinal observational study analyzing 1158 PRU determinations from a cohort of hyper-responders (58%; 119 patients; PRU < 80) undergoing tapering clopidogrel regimen (from 75 mg to 5 mg maintenance dose). Associations between PRU and covariates (age, sex, diabetes, etc.) were evaluated. A Generalized Estimating Equations (GEE) model was fitted to predict the probability of PRU >230 at the subsequent visit during the maintenance phase (≥ day 23), using current PRU and clopidogrel dose as predictors. Results During the maintenance, the GEE model identified current PRU as a strong predictor of subsequent non-response (p = 0.0027), whereas dose variation was not significant (p = 0.58). Each 10-unit increase in PRU was associated with an 18% increase in the odds of future non-response (OR = 1.18). Using an 8% risk threshold, a PRU ≥ 210 defined a high-risk zone, corresponding to a 9.3–12.5% probability of PRU > 230 at the next assessment. Conclusions Current PRU levels are the primary determinant anticipating loss of platelet inhibition during clopidogrel maintenance. The proposed decision rule (alert threshold at PRU ≥ 210) offers a quantitative framework for personalized monitoring and dose adjustment in patients treated for cerebral aneurysms. Conflict of interest Marta Aguilar-Perez: nothing to disclose