Abstract TP161: Evaluation Of On-treatment Platelet Reactivity During Carotid Artery Stenting Using The VerifyNow System

Abstract

OBJECTIVE: We evaluated the correlation between point-of-care measurement of on-treatment platelet reactivity and postoperative thromboembolic events in patients undergoing carotid artery stenting (CAS) for atherosclerotic carotid artery stenosis. METHODS: Thirty patients receiving dual antiplatelet treatment, including clopidogrel, before CAS were prospectively enrolled. On-treatment platelet reactivity was measured within 24 h before CAS using both the VerifyNow P2Y12 and aspirin assays and light transmittance aggregometry (LTA) with ADP (LTA-ADP) and collagen (LTA-collagen) as the agonists. The endpoint was defined as the detection of acute ipsilateral ischemia on diffusion-weighted imaging (DWI) within 72 h after CAS. Cut-off values for high on-treatment platelet reactivity were established by receiver operating characteristic curve analysis. RESULTS: A significant correlation was observed between VerifyNow P2Y12 reaction units (PRUs) and LTA-ADP and between VerifyNow aspirin reaction units (ARUs) and LTA-collagen. Small abnormalities were observed on DWI in 9 patients (30.0%), and transient ischemic attack was found in 2 (6.67%). Patients with ischemic events had significantly higher mean pre-CAS PRU values (286.42 ± 85.95 vs. 195.28 ± 90.05; p = 0.027) and lower mean pre-CAS PRU percent inhibition (11.71 ± 12.40 vs. 41.52 ± 22.51; p = 0.0027) than those without ischemic events. In the univariate analysis of the endpoint, 4th quartile PRU values (risk ratio [RR]: 3.0; 95% confidence interval [CI]: 1.00-8.92; p = 0.0533), 1st quartile PRU percent inhibition (RR: 6.33; 95% CI: 1.57-25.42; p = 0.0021), and 4th quartile LTA-ADP (RR: 3.06; 95% CI: 1.17-8.00; p = 0.0341) were found to increase the risk of abnormality detection on postprocedural DWI. The optimal cut-offs for high on-treatment platelet reactivity were 264 for pre-CAS PRU values (area under the curve [AUC]: 0.82; 95% CI: 0.65-0.99), 29 for PRU percent inhibition (AUC: 0.89; 95% CI: 0.77-1.01), and 38 for LTA-ADP (AUC: 0.80, 95% CI: 0.67-0.98). CONCLUSION: This study indicates that the new point-of-care VerifyNow P2Y12 assay might help identify patients who are at higher risk for thromboembolic events after CAS.