Clopidogrel Resistance by P2Y12 Platelet Function Testing in Patients Undergoing Neuroendovascular Procedures: Incidence of Ischemic and Hemorrhagic Complications

Abstract

Purpose: The purpose of the study was to assess clopidogrel resistance and whether “intensified” antiplatelet therapy guided by platelet inhibition tests during neuroendovascular procedures would reduce ischemic complications.
Methods: We conducted a retrospective review of patients at Mayo Clinic in Jacksonville, Florida, who
underwent neuroendovascular (NV) procedures and had P2Y12 platelet function testing from October 1,
2009, to September 30, 2010. The primary end-point was to determine P2Y12 resistance to antiplatelet
therapy in patients who underwent NV procedures. Secondary objectives included incidence of hemorrhagic and ischemic events and a correlation between resistance and genetic CYP2C19 testing.
Results: 160 patients underwent P2Y12 platelet function tests. Eighty-one patients (81/160, 50.6%) met
inclusion criteria. Platelet function tests identified 64 patients (79%) as non-resistant (≥20% P2Y12 inhibition) and 17 (21%) as resistant (<20% inhibition) after initial clopidogrel loading. There was an increased
rate of death when a complication occurred in the resistant group by 30 day (17% versus 3%; p=0.059) and
90 day follow-up (23% versus 4%; p=0.032). There was no significant association found between complication and loading dose (p=0.0721).
Conclusions: 21% of patients undergoing NV procedures were resistant to clopidogrel. Intensifying antiplatelet therapy to achieve ≥20% inhibition on platelet function testing did not result in higher numbers of
ischemic or hemorrhagic events, but there was a trend toward more death in the resistant group by 30 and
90 days of those experiencing complication(s)