Evaluation of clopidogrel response with light transmission aggregometry before extra- intracranial stenting

Objective – to study the result of light transmission aggregometry with ADP for platelet reactivity before and after clopidogrel administration before extra-intracranial stenting.Materials and methods. Between January and October 2019 36 patients (19 males and 17 females, the average age was 41 years (25–69 years)) who underwent extra or intracranial stenting for atherosclerotic stenosis, endovascular aneurysm coiling with stent-assistance, or implantation of flow diverter were examined. Determination of the aggregation curve with ADP (concentration – 5 mmol/L) was performed before antiplatelet therapy and 5–7 days after before the procedure. Clopidogrel resistance was determined with a maximum aggregation > 50 % on the aggregation curve. In case of clopidogrel resistance, the daily and loading doses were increased to 150 and 450 mg respectively.Results. The maximum ADP-induced aggregation before clopidogrel admission was 77.50 % [63.0–99.0] and 43 % [33.0–61.0] after admission (p < 0.0001). Clopidogrel resistance was detected in 6 (16.7 %) patients. All patients with low sensitivity to clopidogrel underwent extra or intracranial stenting without peri-procedural complications. Thromboembolic complications occurred in 2 patients with a normal response in the early postoperative period after stent implantation, and in 1 case there was a hemorrhagic complication on standard dual antiplatelet therapy in the form of recurrent bleeding from the femoral artery puncture site.Conclusions. Light transmission aggregatometry with ADP is an effective and relatively cheap method of determination the clopidogrel response before neurovascular stenting. Platelet response to clopidogrel therapy significantly varies among patients. Maximum ADP-induced aggregation on the standard dose of clopidogrel before stenting is an important prognostic factor for deciding the optimal clopidogrel dosage. Therapeutic approaches to reduce platelet aggregation in patients with low response on a standard clopidogrel therapy require further study with the aim to determine the optimal drug and its dose for reducing thrombembolic complications rate, without additional risk of hemorrhagic ones.