HORIZONS-AMI Stent and Drug Cohort Data Presented

September 25, 2009—Boston Scientific Corporation (Natick, MA) announced 2-year follow-up data from the stent cohort of the HORIZONS-AMI (Harmonizing Outcomes With Revascularization and Stents in Acute Myocardial Infarction) trial, which is designed to determine the safety and efficacy of the company's Taxus Express2 paclitaxel-eluting coronary stent system compared to bare-metal stents (BMS) in patients experiencing an acute myocardial infarction (AMI). HORIZONS-AMI has enrolled 3,006 patients worldwide. Analysis of the data was presented at the Transcatheter Cardiovascular Therapeutics (TCT) 2009 scientific symposium in San Francisco.

"Results from the HORIZONS-AMI trial showed impressive and sustained efficacy benefits at 2 years for patients treated with Taxus Express2 stents when compared to BMS in patients with AMI," commented Gregg W. Stone, MD, principal investigator. "The data also showed comparable safety outcomes for the Taxus Express2 and BMS. This study should continue to inform how decisions are made regarding the use of drug-eluting stents in high-risk AMI patients during the early hours of a heart attack."

According to the company, HORIZONS-AMI demonstrated that the Taxus Express2 stent significantly reduced angiographic restenosis compared to an otherwise identical bare-metal Express control stent. After 2-year follow-up, the primary efficacy endpoint of ischemia-driven target lesion revascularization (TLR) was 6.8% for patients treated with drug-eluting stents (DES) versus 11.6% for BMS (P < .001), a reduction of 42%. The secondary efficacy endpoint of ischemia-driven target vessel revascularization (TVR) was 8.9% for DES versus 13.3% for BMS (P < .001), a reduction of 34%.

The primary safety endpoint of major adverse cardiac events at 2 years was comparable among DES and BMS patients (11% vs 11.2%, respectively; P = .9), which is consistent with 1-year findings. Individual rates of death, repeat heart attack, stroke, and stent thrombosis between the two groups through 2 years of follow-up were also comparable, even after correction for any measured baseline differences. Adverse events between 1 and 2 years showed that all-cause death was lower among DES patients (0.8% for DES vs 1.8% for BMS; P = .04), ischemia-driven TLR was lower among DES patients (2.6% for DES vs 4.7% for BMS; P = .006), and ischemia-driven TVR showed similar lower rates with DES compared to BMS (3.4% for DES vs 5.2% for BMS; P = .03).

The company advised that the Taxus Express2 stent and the Express stent are not specifically indicated by the US Food and Drug Administration for use in patients with AMI.

According to the conference newspaper, TCT Daily, the drug cohort of HORIZONS-AMI is a randomized multicenter trial that compared bivalirudin (Angiomax, The Medicines Company, Parsippany, NJ) to heparin plus a glycoprotein IIb/IIIa inhibitor in 3,602 ST-elevation myocardial infarction patients. Of these patients, 3,006 were eligible for randomization, in a 3:1 ratio, to either Taxus Express2 DES or Express BMS. Dr. Stone, MD, also presented the HORIZONS-AMI drug cohort findings.

At 2 years, bivalirudin significantly reduced noncoronary artery bypass grafting major bleeding by 36%, reinfarction by 25%, cardiac mortality by 41%, and all-cause mortality by 25%. The bivalirudin and heparin-plus-glycoprotein IIb/IIIa arms had comparable rates of stent thrombosis, TVR, and stroke.

"We had noticed at 1 year that there was a slight spreading of the curves for reinfarction favoring bivalirudin, and that trend continued over 2 years. Interestingly, reinfarctions continued to accumulate in the heparin-plus-glycoprotein IIb/IIIa inhibitor arm, while the curve was much flatter in the bivalirudin arm," Dr. Stone said, adding that it is possible that reinfarction may be affected by early bleeding, much like long-term mortality.