Drug-Eluting Stents Show Safety, Efficacy in AMI


ATLANTA — Drug-eluting coronary stents were at least as safe and effective as bare-metal stents for treating patients with an acute MI in a pair of studies that each involved 600–700 patients.

One study compared the outcomes after 1 year in patients treated with sirolimus-eluting stents or bare-metal stents; the second report involved a comparison of paclitaxel-eluting stents with bare-metal stents after 1 year. The results were reported at the annual meeting of the American College of Cardiology.

Although the results from both trials seemed to show that drug-eluting stents (DESs) were safe when implanted in patients with an acute MI (AMI)—and in the case of sirolimus-eluting stents also showed a reduced need for target vessel revascularization during follow-up—the reaction of experts to the results highlighted the degree of uncertainty about the safety of DESs in this clinical setting.

“The data for drug-eluting stents in acute MI is very mixed. Some study results suggest safety; others suggest possible harm,” commented Dr. Gregg W. Stone, of the division of cardiology at Columbia University, New York. “I think we need results from a large, randomized, controlled study to understand the safety and efficacy of drug-eluting stents in the prothrombotic environment of acute MI. Such a trial is now being done, the HORIZONS [Harmonizing Outcomes with Revascularization and Stents] AMI study, which will enroll 3,400 patients.” Dr. Stone is the principal investigator for HORIZONS AMI.

But other experts contend that they are comfortable using DESs now for the primary treatment of acute MI.

“I've used drug-eluting stents for primary PCI [percutaneous coronary intervention] for at least the past 2 years,” said Dr. Eric R. Bates, a professor of medicine at the University of Michigan, Ann Arbor.

Speaking in a separate talk at the meeting, Dr. Bates acknowledged that results from the HORIZONS AMI trial will help settle the issue. But, he added, “for those who wish to use drug-eluting stents now, you can find some evidence to support it. For those who want to continue to use bare-metal stents, it's fair to do that until more evidence is forthcoming.”

So far, there is no evidence that the risk of thrombosis is increased when DESs are used during primary PCI. It is also possible, but not yet proved, that the extra cost for DESs is balanced by a reduced rate of rehospitalization, said Dr. Bates. But the ability of DESs to reduce the need for target vessel revascularization, compared with that of bare-metal stents, may be blunted in this setting because restenosis may not be that big a problem when bare-metal stents are used for primary PCI. This may mean that the best approach is selected use of DESs, such as in narrow coronary arteries or for long lesions.

The study comparing sirolimus-eluting and bare-metal stents was done at 48 centers in Europe. The TYPHOON (Trial to Assess the Use of the Cypher Stent in Acute Myocardial Infarction Treated with Angioplasty) study was sponsored by Cordis Corp., which markets the sirolimus-eluting stent (Cypher). Patients entered the study if they first presented within 12 hours from the onset of symptoms of acute MI that required primary PCI in a native coronary artery. The study's primary end point was the rate of target vessel failure by 1 year after treatment—a composite of all target vessel-related death, recurrent MI, or need for target vessel revascularization.

The rate for this end point was 7.3% in 355 patients treated with a sirolimus-eluting stent and 14.3% in 357 patients treated with a bare-metal stent, a statistically significant difference, reported Dr. Christian Spaulding, of the Assistance Publique-Hôpitaux de Paris. This difference was driven primarily by a difference in the rate of need for revascularization, which was 5.6% in patients treated with a sirolimus-eluting stent and 13.4% in those who got a bare-metal stent.

Treatment with a sirolimus-eluting stent appeared safe, with stent thrombosis rates of 3.4% throughout all 12 months of follow-up, and 0.3% after the first 30 days following treatment. In the bare-metal stent group, the overall rate of stent thrombosis was 3.6%, which included a 0.6% rate after 30 days. Patients were directed to take aspirin and clopidogrel daily for at least 6 months after stent placement, said Dr. Spaulding.

The study of the paclitaxel-eluting stent (Taxus) was done at two hospitals in the Netherlands. The PASSION (Randomized Comparison of Paclitaxel-Eluting Stent Versus Conventional Stent in ST-Segment Elevation Myocardial Infarction) study did not have any industry support.

During 2003–2004, researchers enrolled patients with symptoms of AMI who had a culprit lesion in a native coronary artery. The primary end point was the combined rate of cardiac death, recurrent MI, or need for target lesion revascularization during the first year of follow-up.


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