Efficacy of Monitoring for Multiple Antiplatelet Therapy during Intracranial Stent Placement: A Preliminary Study.

Objective: During cerebral aneurysm embolization using intracranial stents, platelet aggregation increases owing to increased wall shear stress and a loss of vascular endothelial function at the stent implantation site. Preoperative multiple antiplatelet therapy was introduced to prevent severe thromboembolic complications due to increased platelet aggregation. However, specific guidelines for the administration and pharmacological evaluation of this therapy do not exist currently. We examined the benefits of perioperative platelet aggregation monitoring in a cohort of patients. Methods: We had 377 patients with unruptured intracranial aneurysms who underwent stent-assisted embolization at our hospital between December 2012 and November 2019. We ultimately included 181 patients in our final analysis. These patients were continuously administered aspirin (100 mg/day) and clopidogrel (75 mg/day) for more than 5 days before the procedure to the post-procedural period. Of these patients, 30 patients who underwent light transmission aggregometry (LTA) before procedure, post-procedure (3 days after procedure), and at first post-discharge clinic visit were included as the subjects. The following characteristics were studied: age; sex; presence/absence of hypertension, dyslipidemia, and/or diabetes mellitus; location of aneurysm; type/number of stent; technique for stent placement; duration of preoperative multiple antiplatelet therapy; perioperative platelet aggregation test results; and postoperative ischemic or hemorrhagic complications. Results: Among these 30 patients, the median duration of antiplatelet therapy prior to the preoperative platelet aggregation measurements was 7 (interquartile range [IQR]: 6-8) days, and post-discharge measurement of LTA was performed at a median period of 27 (IQR: 22-35.5) days after procedure. The preoperative, postoperative, and first post-discharge clinic visit LTA values for adenosine diphosphate (ADP)-induced platelet aggregation were 50% (IQR: 44-54%), 42.5% (IQR: 36-48%), and 36% (IQR: 32-40%), respectively. These results represented gradual decrease in LTA values and a significant difference between the preoperative and post-discharge values. The LTA values for collagen aggregation showed a significant difference evident between the preoperative and post-discharge values; preoperative 38% (IQR: 27-60%), postoperative 42% (IQR: 30-58%), post-discharge 28% (IQR: 20-42%), respectively. We had one thromboembolic complication and one hemorrhagic complication. The results indicated that appropriate platelet aggregation monitoring during multiple antiplatelet therapy prevents thromboembolic complications such as stent thrombosis. However, we also found that many patients demonstrated increased postoperative platelet aggregation inhibitory effects due to the postoperative continuation of the same multiple antiplatelet therapy that was used preoperatively. Conclusion: This study demonstrates that postoperative, continuous, oral antiplatelet therapy induces increased platelet aggregation inhibition effects, which may lead to hemorrhagic complications. Therefore, continued platelet aggregation monitoring after surgery may be important to allow for any necessary alterations to the therapeutic dose and regimen.