Study Finds No Increased Stent Thrombosis With DES

March 29, 2009—The American College of Cardiology announced that a new analysis of the HORIZONS-AMI trial found that in patients who undergo percutaneous coronary intervention (PCI) because of an acute myocardial infarction (MI), the overall risk of late stent thrombosis is just over 3%, but it does not appear to be higher with drug-eluting stents, nor is it influenced by the choice of anticoagulants evaluated in the trial.

According to George Dangas, MD, the present study is the largest comparative trial of different stent types and anticoagulant regimens in patients with acute MI. The findings document a considerably high rate of stent thrombosis within 1 year after primary angioplasty. However, the rates were comparable between drug-eluting and bare-metal stents, and between bivalirudin and heparin plus glycoprotein IIb/IIIa inhibitors.

For the study, investigators analyzed data from 3,202 patients who were treated with stenting in the main HORIZONS-AMI trial. Within 1 year, stent thrombosis occurred in 107 patients (3.4%). Of these, 0.9% of cases were acute (< 24 hour after stent implantation), 1.6% were subacute (1 to 30 days), and 1% were late (1 to 12 months). The 1-year rate of stent thrombosis was identical among patients treated with either drug-eluting or bare-metal stents. Among patients who received bivalirudin, the rate of 1-year stent thrombosis was 3.6%, as compared to 3.2% among patients who received heparin plus glycoprotein IIb/IIIa inhibitors, a statistically nonsignificant difference. There were, however, fluctuations in the rates over time: patients treated with bivalirudin had a higher rate of acute stent thrombosis, but there was a catch-up stent thrombosis in the other group by 1 month.

Investigators also collected data on a large number of variables that might influence the risk of stent thrombosis. Characteristics that independently predicted the risk of stent thrombosis during the year following stent implantation included ongoing cigarette smoking, insulin-treated diabetes, use of a high number of stents, treatment of ulcerated lesions, and complete blockage of the artery responsible for the heart attack upon initial x-ray angiography. Use of a high loading dose of the anticlotting drug clopidogrel (600 mg) was a protective factor, the investigators found.