Increased risk in patients with high platelet aggregation receiving chronic clopidogrel therapy undergoing percutaneous coronary intervention: is the current antiplatelet therapy adequate?

J Am Coll Cardiol. 2007 Feb 13;49(6):657-66. doi: 10.1016/j.jacc.2006.10.050. Epub 2007 Jan 26.


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.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Aged
  • Angioplasty, Balloon, Coronary / adverse effects*
  • Clopidogrel
  • Female
  • Humans
  • Male
  • Middle Aged
  • Myocardial Ischemia / etiology
  • Myocardial Ischemia / prevention & control*
  • Platelet Aggregation / drug effects*
  • Platelet Aggregation Inhibitors / therapeutic use*
  • Platelet Glycoprotein GPIIb-IIIa Complex / antagonists & inhibitors
  • Recurrence
  • Stents
  • Thrombelastography
  • Ticlopidine / analogs & derivatives*
  • Ticlopidine / therapeutic use


  • Platelet Aggregation Inhibitors
  • Platelet Glycoprotein GPIIb-IIIa Complex
  • Clopidogrel
  • Ticlopidine