ABSTRACT NUMBER: ESOC2026A1026 REAL WORLD ADHERENCE AND OUTCOME OF CYP2C19-GUIDED DUAL ANTIPLATELET THERAPY USING LAB-BASED GENOTYPING IN STROKE MANAGEMENT

Abstract Background and aims CYP2C19 loss-of-function (LOF) allele carriers benefit from ticagrelor-aspirin over clopidogrel-aspirin for secondary stroke prevention. However, implementing CYP2C19-guided dual antiplatelet therapy (DAPT) is challenging in centers relying on lab-based testing with prolonged turnaround time. This study evaluates adherence to CYP2C19-guided DAPT using lab-based genotyping and its impact on 90-day recurrent stroke and composite vascular events. Methods We conducted a single-centre retrospective study (2023-2024) involving minor and transient ischemic stroke patients. Patients were initially treated with ticagrelor-aspirin or clopidogrel-aspirin based on clinicians’ preference. Following lab-based CYP2C19 genotype results, antiplatelet was switched when indicated with adherence defined as final treatment consistent with genotype results (LOF allele carrier receiving ticagrelor and non-LOF allele carrier receiving clopidogrel). Results Of 167 acute ischemic stroke patients, 86 (51.5%) were LOF allele carriers and 81 (48.5%) were non-LOF allele carriers. Median age was 63 years and median CYP2C19 test turnaround time was 2 (1-4) days. Overall adherence to CYP2C19-guided antiplatelet therapy was 67.7% where LOF allele carriers was 59.3% and non-LOF allele carriers was 40.7% (p=0.004). Recurrent stroke occurred within 90 days in 8 patients (9.3%) among LOF carriers and 2 patients (2.5%) among non-LOF carriers (OR 7.54[95%CI 1.35-42.02],p=0.021). Adherence to CYP2C19-guided antiplatelet therapy resulted in significant reduction of 90-day recurrent stroke (OR 0.12 [95%CI 0.03-0.58], p=0.008) but a non-significant reduction in composite vascular event (OR 0.31[95%CI 0.09-1.10], p=0.07). Conclusions Adherence to CYP2C19-guided antiplatelet therapy with lab-based genotyping may reduce 90-day recurrent stroke and composite vascular events. Conflict of interest Chia Xuan Teoh: nothing to disclose