Delayed Clopidogrel Hyper-response after Neuroendovascular Therapy Associated with Hemorrhagic Complications

Objective: Changes in the VerifyNow (Accumetrics, San Diego, CA, USA) assay results before and after neuroendovascular therapy and complications were evaluated. Methods: Of the 124 neuroendovascular procedures at our hospital between June 2014 and June 2015, 15 patients received elective treatment with dual-antiplatelet therapy (DAPT) consisting of aspirin at 100 mg/day and clopidogrel at 75 mg/day continued from at least 7 days before the procedure to the postprocedural period. Of these patients, those who underwent the VerifyNow assay before treatment and within 1 month after the procedure were included. Changes in the results of VerifyNow assay and complications were retrospectively evaluated. Results: Thirteen patients were included. The treatment was coil embolization of intracranial aneurysm in five patients (stent-assisted in four patients), carotid artery stenting in seven patients, and angioplasty and stenting for intracranial atherosclerosis in one patient. No significant change was observed in the aspirin reaction units (ARU) value after compared with before treatment. The P2Y12 reaction units (PRU) value decreased significantly after treatment (152 [interquartile range (IQR): 126 - 157] vs. 9 [IQR: 6 - 61], p = 0.001). Hemorrhagic events were observed in eight patients (61.5%) after treatment. Conclusion: Continuation of DAPT after neuroendovascular treatment may induce delayed clopidogrel hyper-response, which may lead to hemorrhagic complications.