HORIZONS-AMI: No additional stent thrombosis at one year with paclitaxel-eluting stent

One-year thrombosis rates were also similar in patients taking bivalirudin compared with those taking glycoprotein IIb/IIIa inhibitors.

Rates of stent thrombosis at one year were similar in patients taking bivalirudin compared with those taking glycoprotein IIb/IIIa inhibitors, results from an analysis suggested.

Researchers for the HORIZONS-AMI trial randomly assigned 3,602 patients with acute MI undergoing primary percutaneous coronary intervention to either bivalirudin monotherapy (n=1,800) or unfractionated heparin plus a glycoprotein IIb/IIIa inhibitor (n=1,802). Patients were then randomized 3:1 and received either a paclitaxel-eluting stent (Taxus, Boston Scientific) or a bare metal stent (Express, Boston Scientific).

The researchers reported that stent thrombosis following stent implantation occurred in 107 (3.3%) patients, and occurred frequently within the first 24 hours (0.9%), between one and 30 days (1.6%) and between one month and one year (1%). They also reported no difference in the rates of acute stent thrombosis between those patients randomized to bivalirudin monotherapy and glycoprotein IIb/IIIa inhibitors at one year. Patients in the bivalirudin group had higher rates of acute stent thrombosis within the first five hours following stent implantation, but comparable rates after one day. There was no difference in one-year stent thrombosis rates between patients implanted with any drug-eluting stent and a bare metal stent (3.3% vs. 3.4%, P=.93).

“The results of the current analysis suggest that optimizing adjunct pharmacology with bivalirudin during primary PCI may further improve outcomes, since randomization of unfractionated heparin attenuated the risk of acute stent thrombosis and a 600 mg loading dose of clopidogrel [Plavix, Sanofi Aventis] attenuated the risk of sub-acute stent thrombosis,” George D. Dangas, MD, PhD, an associate professor of medicine at Columbia University Medical Center in New York, said in his presentation today at the American College of Cardiology’s 58th Annual Scientific Sessions. “Whether a prolonged bivalirudin infusion post-PCI or an even more potent and rapid-acting thienopyridine agent might further reduce early stent thrombosis in patients with STEMI treated with bivalirudin without increasing bleeding warrants further study”

Apart from noting that the results from HORIZONS-AMI suggested a reduction in mortality, E. Magnus Ohman, MD, a professor of medicine at Duke Heart Center in Durham, N.C., urged caution about prolonging antithrombin therapy.

“The issue that was discussed is whether prolonging antithrombin therapy with bivalirudin should be tested before adopted,” Ohman said in the discussant portion of the trial presentation. “I would caution that the literature that extends antithrombin therapy in this field is actually associated with more bleeding, so it may actually lose the value of the simplified strategy that was tested in HORIZONS-AMI trial.” – by Eric Raible

For more information:

Dangas G. Predictors of stent thrombosis after primary angioplasty in acute MI: The HORIZONS-AMI trial. #2406. Presented at: 58th American College of Cardiology Annual Scientific Session; March 29-31, 2009; OrlandoFla.