C erebral infarction is one of the major disabling complications of neurovascular stent treatment. During the last decades, many studies have evaluated the safety and efficacy of the technique of stent placement for intracranial aneurysms, which demonstrated a range of 3.7%-21% thromboembolic complications. 4,10,11,29 Dual antiplatelet therapy (aspirin and clopidogrel) has been used as the standard protocol to decrease the incidence of thromboembolic complications in patients with intracranial aneurysms undergoing stent treatment. However, many patients still experience thromboembolic complications after neurovascular intervention, despite being compliant with the standard antiplatelet medication protocol.Previous studies have demonstrated that a low response to antiplatelet medication was associated with the abbreviatioNs AA = arachidonic acid; ADP = adenosine diphosphate; DWI = diffusion-weighted imaging; ICA = internal carotid artery; MA = maximum amplitude; mRS = modified Rankin Scale; TEG = thromboelastography. obJective Insufficient platelet inhibition has been associated with an increased incidence of thromboembolic complications in cardiology patients undergoing percutaneous coronary intervention. Data regarding the relationship between insufficient platelet inhibition and thromboembolic complications in patients undergoing neurovascular procedures remain controversial. The purpose of this study was to assess the relationship of insufficient platelet inhibition and thromboembolic complications in patients with intracranial aneurysm undergoing stent treatment. methods The authors prospectively recruited patients with intracranial aneurysms undergoing stent treatment and maintained the data in a database. MRI with diffusion-weighted sequences was performed within 24 hours of stent insertion to identify acute ischemic lesions. The authors used thromboelastography to assess the degree of platelet inhibition in response to clopidogrel and aspirin. Univariate and multivariate logistic regression analysis was used to identify potential risk factors of thromboembolic complications. results One hundred sixty-eight patients with 193 aneurysms were enrolled in this study. Ninety-one of 168 (54.2%) patients with acute cerebral ischemic lesions were identified by diffusion-weighted MRI. In 9 (5.4%) patients with ischemic lesions, transient ischemic attack or stroke was found at discharge, and these complications were found in 11 (6.5%) patients during the follow-up period. The incidence of periprocedural thromboembolic complications increased with resistance to antiplatelet agents, hypertension, hyperlipidemia, complete occlusion, and aneurysm of the anterior circulation. The multivariate regression analysis demonstrated that the anterior circulation and adenosine diphosphate (ADP) inhibition percentage were independent risk factors of perioperative thromboembolic complications. The maximum amplitude and ADP inhibition percentage were independent risk factors for thromboembolic complications during the follow-up peri...