A Multi-Center Evaluation of Clopidogrel Resistance and its Role in Predicting Stent Thrombosis in Transcarotid Artery Revascularization

Clopidogrel resistance testing is not routine prior to transcarotid artery revascularization (TCAR) and resistance rates are not well described in this setting despite frequent use of periprocedural clopidogrel. We compared 2 resistance testing modalities to determine the relationship between resistance and stent outcomes. Consecutive patients undergoing TCAR at 3 institutions were retrospectively identified. Clopidogrel-resistance testing results and outcomes were described. A total of 210 patients underwent TCAR from 2018-2022. One hundred fifty four (73%) were on dual antiplatelet therapy (DAPT) for at least 7 days prior to TCAR. Twenty-nine patients were not on DAPT due to therapeutic anticoagulation and most (38/56, 68%) received a loading dose of a second antiplatelet the day of surgery. Twenty-five patients (11.9%) experienced stent thrombosis within 30 days. Patients not on DAPT for at least 7 days prior to surgery were more prone to stent thrombosis (16.7% vs. 10.4%, P = 0.164). More than half (133/210, 63%) of patients underwent resistance testing, 25 with thromboelastography with platelet mapping (TEG-PM), 103 with VerifyNow P2Y12 platelet reactivity assay, and 5 with both. Prevalence of Clopidogrel resistance among tested patients was 41%. In patients tested using both TEG-PM and VerifyNow, agreement was poor (Cohen's Kappa -0.05). Among patients with resistance, 12 (22%) experienced stent thrombosis. Comparatively, 8 (10%) patients without resistance developed thrombosis (P = 0.021). VerifyNow P2Y12 platelet reactivity assay correctly predicted Clopidogrel resistance more accurately than TEG-PM (70% vs. 40%, P = 0.025) and had sensitivity of 56% and specificity of 73% for stent thrombosis. Our multi-institutional cohort confirms a high rate of Clopidogrel resistance in patients undergoing TCAR, with higher acute stent thrombosis rates noted in patients with resistance. VerifyNow P2Y12 platelet reactivity assays more reliably predict Clopidogrel resistance than TEG-PM.