Precision of VerifyNow P2Y12 Assessment of Clopidogrel Response in Patients Undergoing Cerebral Aneurysm Flow Diversion

Abstract Background Dual antiplatelet therapy (DAT), most commonly with aspirin and Clopidogrel, is the standard of care for intracranial stenting, including flow diversion. Clopidogrel response varies by individual. Objective To investigate the real-world precision of VerifyNow P2Y12 assessment (Accumetrics, San Diego, California) of Clopidogrel response. Methods Using a prospectively-collected, IRB-approved cerebral aneurysm database 643 patients were identified who were treated with the Pipeline embolization device from 2011 to 2017. Patients with multiple P2Y12 assays drawn within a 24-h window were identified. A single patient could contribute multiple, independent sets. Levels drawn before a 5-d course of DAT and patients who received alternative antiplatelet agents were excluded. Therapeutic range was defined as platelet reaction units (PRU) 60–200. Results A total of 1586 P2Y12 measurements were recorded; 293 (46%) patients had more than one assay. One hundred forty (22%) patients had multiple P2Y12 measurements within 24 h. These patients accounted for 230 independent 24-h sets. The average P2Y12 fluctuation across all sets was 35 points; the 25th, 50th, and 75th percentiles were 12, 26, and 48 points, respectively. Of the 230 24-h sets of P2Y12 assays, 76% remained within their original therapeutic category: 100 (43%) all therapeutic, 54 (23%) all hypo-responsive, and 21 (9%) all hyper-responsive. Twenty-four percent of patients fluctuated between therapeutic categories when multiple P2Y12 assessments were drawn within a 24-h period: 29 (13%) between hypo-response and therapeutic, 23 (10%) between hyper-response and therapeutic, and 3 (1%) between hypo-response and hyper-response. CONCLUSION Our experience suggests P2Y12 is an often-imprecise measure, and this should be considered when utilizing P2Y12 levels for clinical decisions.