Abstract Number: LBA4 Platelet Function Testing and Acute Thrombotic Events in Intracranial Aneurysm Patients Undergoing Flow Diversion
Authors: Al‐Kawaz Mais , Shoirah Hazem , Shigematsu Tomoyoshi , Kellner Christopher , De leacy Reade , Fifi Johanna , Majidi Shahram , Mocco J 
Published: April 2023

Introduction
Introduction The role of platelet function testing in patients with intracranial aneurysms undergoing flow diversion remains controversial with limited evidence of its influence on thrombotic outcomes. We report an observational cohort analysis evaluating the association of P2Y12 assay testing with thrombotic events in patients undergoing flow diversion.

Methods
We performed a retrospective review of our prospectively maintained procedural database to identify patients who underwent flow diversion between January 2020 and July 2022. One physician within our practice never performs P2Y12 assay testing. All other physicians utilize P2Y12 assay testing as part of routine practice. These two different patient cohorts were compared. Acute thrombotic events were our primary outcome. Secondary outcomes included delayed intracerebral hemorrhage, intimal hyperplasia without clinical sequalae, and transient neurologic deficits.

Results
We identified 150 patients who underwent flow diversion at our institution between January 2020 and July 2022. Median age was 59 years old (Interquartile range (IQR) 49–67), with 113 females (82.5%) and 24 males (17.5%). Out of 150 patients, 93 (62.0%) patients were treated by physicians who performed routine pre and postoperative testing of aspirin and Plavix assays, with subsequent adjustment of antithrombotic dosing accordingly, while 57 patients (38.0%) were treated by the single physician who prescribes aspirin and clopidogrel pre‐operatively without testing. In all, seven out of 150 patients (4.7%) had an acute thrombotic event requiring intraarterial anti‐thrombotic infusion or urgent thrombectomy, or both. Of these, six where from the 93 patient testing cohort (6.5%), and one in 57 patients non‐testing cohort (1.8%) (p = 0.2). Patients who had a thrombotic event were more likely to have underlying atrial fibrillation (28.6% vs 4.9%, p = 0.01) but otherwise had similar demographics, vascular risk factors, maximal aneurysmal diameter, and parent vessel diameter (Table 1). In a multivariable analysis adjusting for age, maximal aneurysm diameter, ruptured aneurysms, and atrial fibrillation, P2Y12 sensitivity assay testing was not significantly associated with acute thrombotic events in aneurysm patients undergoing flow diversion (Odds Ratio (OR) = 0.15, 95% Confidence Interval (CI) = 0.01‐2.67), p = 0.2). Secondary outcomes were also comparable between both groups; transient neurologic deficits were noted in 4/93 in the testing group (4.3%), and 6/57 in the non‐testing group (10%) (p = 0.14), intracranial hemorrhage occurred in only 2 patients, both in the testing group (p = 0.3), and mild intimal hyperplasia was observed in 18.3% in the testing group versus 12.3% in the non‐testing group (p = 0.33).

Conclusions
Platelet function testing showed no significant correlation with thrombotic events or outcomes in our cohort. The role of platelet function testing remains controversial, albeit widely used in patients undergoing flow diversion of intracranial aneurysms.