PurposeVerifyNow antiplatelet assays were performed before and after stenting for various cerebral artery stenoses to determine the effect of the procedure itself to the function of dual antiplatelets given.Materials and MethodsA total of 30 consecutive patients underwent cerebral arterial stenting procedure were enrolled. The antiplatelet pretreatment regimen was aspirin (100 mg daily) and clopidogrel (300 mg of loading dose followed by 75mg daily). VerifyNow antiplatelet assay performed before and right after stenting. The two test results were compared in terms of aspirin-reaction unit (ARU), P2Y12 reaction units (PRU), baseline (BASE), and percentage inhibition. We evaluated occurrence of any intra-procedural in-stent thrombosis or immediate thromboembolic complication, and ischemic events in 1-month follow-up.ResultsThe median Pre-ARU was 418 (range, 350-586). For clopidogrel the medians of the pre-BASE, PRU, and percent inhibition were 338 (279-454), 256 (56-325), and 27% (0-57%). The medians of the post-ARU, BASE, PRU, and percent inhibition after stenting were 469 (range, 389-573), 378 (288-453), 274 (81-370), and 26% (0-79%). There was a significant increase of ARU (p=0.045), BASE (p=0.026), and PRU (p=0.018) before and after stenting. One immediate thromboembolic event was observed in poor-response group after stenting. There was no in-stent thrombosis and ischemic event in 1-month follow-up.ConclusionWe observed a significant increase of platelet reactivity to dual antiplatelet therapy right after stenting procedure for various cerebral arterial stenoses.