Prevalence of clopidogrel non-responders among patients with stable angina pectoris scheduled for elective coronary stent placement

Thromb Haemost. 2003 May;89(5):783-7.


Dual antiplatelet therapy with aspirin and clopidogrel decreases the rate of stent thrombosis in patients undergoing percutaneous coronary intervention (PCI). However, despite intensified antiplatelet treatment, up to 4.7% of the patients undergoing coronary stenting develop thrombotic stent occlusion, suggesting incomplete platelet inhibition due to clopidogrel resistance. We evaluated the percentage of clopidogrel non-responders among 105 patients with coronary artery disease (CAD) undergoing elective PCI. All patients were treated regularly with aspirin 100 mg/d and received a loading dose of 600 mg clopidogrel followed by a maintenance dose of 75 mg/d before PCI. Clopidogrel non-responders were defined by an inhibition of ADP (5 and 20 Mol/L) induced platelet aggregation that was less than 10% when compared to baseline values 4 h after clopidogrel intake. Semi-responders were identified by an inhibition of 10 to 29%. Patients with an inhibition over 30% were regarded as responders. We found that 5 (ADP 5 Mol/L) to 11% (ADP 20 Mol/L) of the patients were non-responders and 9 to 26% were semi-responders. Among the group of non-responders there were two incidents of subacute stent thrombosis after PCI. We conclude that a subgroup of patients undergoing PCI does not adequately respond to clopidogrel, which may correspond to the occurrence of thromboischemic complications. Point-of-care testing may help to identify these patients who may then benefit from an alternative antiplatelet therapy.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adenosine Diphosphate / pharmacology
  • Aged
  • Angina Pectoris / complications
  • Angina Pectoris / epidemiology
  • Angina Pectoris / therapy*
  • Clopidogrel
  • Drug Resistance / physiology*
  • Female
  • Humans
  • Male
  • Middle Aged
  • Platelet Aggregation / drug effects
  • Platelet Aggregation Inhibitors / pharmacology
  • Platelet Aggregation Inhibitors / therapeutic use*
  • Predictive Value of Tests
  • Prevalence
  • Prosthesis Implantation / adverse effects
  • Stents / adverse effects*
  • Thrombosis / etiology
  • Thrombosis / prevention & control
  • Ticlopidine / analogs & derivatives*
  • Ticlopidine / pharmacology
  • Ticlopidine / therapeutic use*


  • Platelet Aggregation Inhibitors
  • Adenosine Diphosphate
  • Clopidogrel
  • Ticlopidine