Abstract 1122‐000231: A Review of Effect of Ticagrelor on Platelet Inhibition in Clopidogrel Non‐Responders Undergoing Neuroendovascular Procedure
Authors: PATEL Priyadarshee , Jabbour Pascal , Tjoumakaris Stavropoula , Gooch Michael , Rosenwasser Robert , Herial Nabeel 
Published: December 2021

Introduction
: Neuroendovascular procedures are becoming more routine in the treatment of intracranial conditions such as aneurysms, arterial stenosis, and ischemic stroke. These patients are frequently treated with antiplatelet agents prior to the procedure to prevent thrombotic complications. The combination of aspirin and a P2Y12 inhibitor such as clopidogrel is often initiated days before elective procedures or as loading doses for emergent procedures. However, some patients may still experience post procedural thrombotic or hemorrhagic complications which may be related to platelet inhibition.

Methods
: A retrospective review of patients who underwent a neuroendovascular procedure from 1/2017 to 12/2019 in a single tertiary care academic hospital. Procedures included flow‐diverting stent placement for aneurysms, intracranial, and cervical carotid artery stenting. Patients undergoing elective procedure were started on Aspirin and Clopidogrel 75 mg daily. Patients undergoing emergent procedures were given loading doses of Aspirin (650 mg) and Clopidogrel (600 mg). P2Y12 assay was checked prior to receiving Platelet inhibitor and from 3–6 hours after Clopidogrel loading dose. Optimal platelet inhibition was classified as reduction in P2Y12 assay by at least 60%. Patients with suboptimal platelet inhibition <60% were given Ticagrelor loading dose (180 mg) and P2y12 assay was rechecked. Patients who did not have complete chart information, patients with AFib requiring DOAC and patients previously on ADP inhibitors, were excluded from analysis.

Results
: Total neuroendovascular procedures requiring stents were 687 over the period of 3 years. mean age of patients was 61 years. This neuroendovascular procedure consisted of aneurysm stenting (239), aneurysm stent‐assisted coiling 112, intracranial stent for failed mechanical thrombectomy 62, carotid artery stent 108. Suboptimal platelet inhibition was noted in 54% (282) of 523 patients after receiving Clopidogrel. After receiving Ticagrelor, optimal inhibition was noted in 80% (226) of 282 patients with median increase of 26%. 62 patients with suboptimal response to Ticagrelor, 47 were started on Prasugrel. Thrombotic complications were noted in 7 patients, 6 of them were noted to have <50% platelet inhibition. Hemorrhagic complications were noted in 17 patients, amongst them >70% platelet inhibition was noted in 14 patients with mean P2Y12 value of 59.

Conclusions
: Patients receiving P2Y12 ADP antiplatelet therapy may have suboptimal platelet inhibition which results in increased thrombotic risk. Patients who have significant platelet inhibition (>70%) after loading dose are at increased risk for hemorrhagic complications. Better platelet inhibition was achieved with Ticagrelor in Clopidogrel hypo‐response patients. In patients with Clopidogrel hyper‐response, dosing was changed to half the dose or alternate day to reduce hemorrhagic complications. As the use of endovascular therapies requiring dual anti‐platelet agents becomes more established, there is an increasing need to develop titration protocols that minimize the risk of thrombotic and hemorrhagic events based on platelet inhibition.