Increased Risk in Patients With High Platelet Aggregation Receiving Chronic Clopidogrel Therapy Undergoing Percutaneous Coronary Intervention: Is the Current Antiplatelet Therapy Adequate?

doi:10.1016/j.jacc.2006.10.050

Journal of the American College of Cardiology

Volume 49, Issue 6, 13 February 2007, Pages 657-666

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Objectives

We sought to determine whether patients receiving chronic clopidogrel therapy undergoing nonemergent stenting who display high on-treatment preprocedural platelet aggregation measured by standard light transmittance aggregometry and thrombelastography (TEG) will be at increased risk for poststenting ischemic events.

Background

Patients exhibiting heightened platelet reactivity to adenosine diphosphate (ADP) might be at increased risk for recurrent ischemic events after coronary stenting.

Methods

A total of 100 consecutive patients receiving chronic antiplatelet therapy consisting of aspirin (325 mg qd) and clopidogrel (75 mg qd) were studied before undergoing nonemergent stenting. Patients were followed for 1 year after coronary stenting for the occurrence of death, myocardial infarction, stent thrombosis, stroke, or ischemia requiring a hospital stay.

Results

All patients were aspirin responsive. Patients with ischemic events (23 of 100, 23%) within 1 year had greater on-treatment prestent ADP-induced platelet aggregation than patients without ischemic events by aggregometry and TEG (p < 0.001 for both measurements). Of patients with an ischemic event, 70% and 87% displayed high on-treatment platelet reactivity at baseline by aggregometry and TEG, respectively. High on-treatment platelet reactivity as measured by aggregometry and TEG were the only variables significantly related to ischemic events (p < 0.001 for both assays). The administration of eptifibatide reduced periprocedural elevation in platelet reactivity, with no significant differences in bleeding events.

Conclusions

Patients receiving chronic clopidogrel therapy undergoing nonemergent percutaneous coronary intervention who exhibit high on-treatment ADP-induced platelet aggregation are at increased risk for postprocedural ischemic events. These findings might have implications for the alteration in clopidogrel maintenance dose and use of glycoprotein IIb/IIIa inhibitors in selected patients.

Abbreviations and Acronyms

arachidonic acid

ADP

adenosine diphosphate

glycoprotein

HPR

high on-treatment platelet reactivity

LTA

light transmittance aggregometry

NPR

normal on-treatment platelet reactivity

PCI

percutaneous coronary intervention

TEG

thrombelastograph(y)

Cited by (0)

: This study was supported by the Sinai Hospital of Baltimore, the National Institute of Health (NIH) grant 5R44HL059753-03, and a grant from Haemoscope Corporation, Niles, Illinois.

¹: Dr. Gurbel has received research funding from Haemoscope and NIH to study the physical properties of clot formation with respect to recurrent ischemic events postelective stenting; research funding from Schering and Millennium to study antiplatelet effects of clopidogrel and eptifibatide in elective stenting; and research grant funding from Bayer to study the antiplatelet effects of aspirin in outpatients.