Clopidogrel nonresponsiveness may predispose to stent thrombosis

March 26, 2007

A new study offers insight into the connection between stent thrombosis with drug-eluting stents (DES) and adherence to antiplatelet therapy. Data from the RECLOSE (Low Responsiveness to Clopidogrel and Sirolimus- or Paclitaxel-eluting Stent Thrombosis) study indicate that nonresponsiveness to clopidogrel is a strong independent risk factor for stent thrombosis in patients receiving DES.

A new study offers insight into the connection between stent thrombosis with drug-eluting stents (DES) and adherence to antiplatelet therapy. Data from the RECLOSE (Low Responsiveness to Clopidogrel and Sirolimus- or Paclitaxel-eluting Stent Thrombosis) study indicate that nonresponsiveness to clopidogrel is a strong independent risk factor for stent thrombosis in patients receiving DES.

The results were presented at the American College of Cardiology's 56th annual scientific session by David Antoniucci, MD.

RECLOSE was a prospective observational study of 804 patients in whom a sirolimus- or paclitaxel-eluting stent was successfully implanted and who were adherent to clopidogrel and aspirin treatment. Using a platelet aggregation test, patients were assessed for platelet reactivity after a loading dose of clopidogrel, 600 mg. In addition to clopidogrel, 75 mg/d, all patients were treated with aspirin, 325 mg/d.

Thirteen percent of the cohort was found to be nonresponders to clopidogrel.

The incidence of stent thrombosis at 6 months was 2.3% in responders to clopidogrel and 8.6% in nonresponders ( p p = 0.009).

Testing for clopidogrel responsiveness before stenting may reveal a group that needs alternate antiplatelet drugs or different dosages, said Dr. Antoniucci, head of cardiology at Careggi Hospital, Florence, Italy. Other options would be to treat nonresponsive patients with bare metal stents or coronary artery bypass graft surgery instead of with DES.

Data from a registry of 1,500 patients treated with sirolimus-eluting stents highlighted the relationship between antiplatelet therapy and stent thrombosis. Data from the registry of real-world use of sirolimus-eluting stents were also announced here. Among patients in the registry, approximately one-fourth discontinued their recommended dual antiplatelet treatment with aspirin and clopidogrel before 1 year.

Surprisingly, adherence to the dual antiplatelet regimen did not result in a statistically significant reduction in mortality or the incidence of myocardial infarction or stent thrombosis at 1 year compared with nonadherence, reported principal investigator George D. Dangas, MD, PhD, who is associate professor of medicine, The Cardiovascular Research Foundation/Columbia University Medical Center, New York.