Introduction: Dual antiplatelet therapy (DAPT) is critical to avoid risk of thromboembolic events in intracranial aneurysm stent treatment. The prevalence of high on-treatment platelet reactivity (HTPR) which can contribute to poor outcomes remains poorly defined among the cerebral aneurysm patient population.
Methods: 252 patients treated with Neuroform Atlas, LVIS, and Pipeline stents in 265 procedures between 2012 and 2018 were included. Patients were started on daily clopidogrel 75 mg and aspirin 325 mg 7-10 days pre-procedurally and underwent platelet aggregation testing using VerifyNow P2Y12 assay on day of procedure (DOP). Patients found to be inadequately inhibited (PRU>170) by clopidogrel in a pre-op office visit, on DOP, or post-procedure were switched to either ticagrelor 90mg bid, or daily prasugrel 10 mg after loading doses. Procedural thromboembolic ischemia was evaluated using diffusion-weighted brain MRI (DW-MRI) within 24 hours.
Results: Patients initiated on clopidogrel (n=230) had PRU=118.2 ± 78 (median 117); but 75/230 (32.6%) were non- or hypo-responders with PRU=186.7 ± 55.5 (median 182) and were switched to an alternate regimen. Hypo-responders switched to ticagrelor had PRU=78.8 ± 61.4 (median 75) and those switched to prasugrel had PRU=57.6 ± 37.9 (median 54). All patients on prasugrel (n=29) had PRU=53.8 ± 42.0 (median 52.1), showing significantly greater inhibition compared to patients started or switched to ticagrelor (n=55) PRU=70.1 ± 57.0 (median 58). Greater platelet inhibition on DOP was significantly associated with absence of DW-MRI lesions on post-procedural MRI (PRU 77.6 vs. 96.9, p <0.03).
Conclusions: Inadequate platelet inhibition by clopidogrel is seen in a third of aneurysm patients undergoing intracranial stenting. Cautious pre-procedural testing and diligent selection of alternate agents with repeat testing on day of procedure can help lower thromboembolic ischemic events in this patient population.
Patient Care: It is hoped that this research will provide neurosurgeons with new insights on the critical role of platelet inhibition and a strategy for testing and mitigating incomplete inhibition to decrease procedural thromboembolic complications in aneurysm patients undergoing intracranial stent therapy.
Learning Objectives: By the conclusion of this session, participants should be able to: 1) Describe the importance of platelet inhibition in decreasing thromboembolic complications during aneurysm stent embolization, 2) Discuss strategies for identifying and mitigating high on-treatment platelet reactivity, and 3) Compare the effectiveness of different anti-platelet regimens.