Measurement of Antiplatelet Inhibition during Neurointerventional Procedures: The Effect of Antithrombotic Duration and Loading Dose

BACKGROUND/OBJECTIVE Symptomatic thromboembolic events are the most common complications associated with aneurysm coiling, and carotid and intracranial stenting. Our objective is to assess the effect of aspirin (ASA) and clopidogrel dose and duration on platelet inhibition using a point of care assay in neurointerventional (NI) suite. METHOD The dose, duration, and point of care platelet function assay data for clopidogrel and aspirin therapy were prospectively collected between February 2006 and November 2007. Inadequate platelet inhibition for ASA was defined as >= 550 ASA reaction units (ARU), and for clopidogrel was defined as <= 50% inhibition of the P2Y12/ADP receptor RESULTS We collected data from 216 consecutive patients. Inadequate platelet inhibition was noted in 13% of patients on aspirin and 66% of patients on clopidogrel (P-value < .0001). Patients taking clopidogrel 75 mg for >= 7 days, 300 mg for 24 hours, and 600 mg same day load had a mean P2Y12/ADP inhibition of 45%, 35% (P-value = .09), and 16%, respectively (P-value = .005). CONCLUSION Premedication with clopidogrel, in contrast to aspirin, does not achieve adequate platelet inhibition in about two-third of the patients. Same day antiplatelet loading may be insufficient to achieve adequate platelet inhibition and should be avoided if clinically feasible.