Controversy has led to small fall in sales of drug eluting stents

Fears about the safety of drug eluting stents have been reawakened this week with the publication of an article on the apparently thrombogenic effect of these devices.

The article in the New England Journal of Medicine (2006;355:1949-52) outlines the history of fears about the devices, explains how the US Food and Drug Administration and the manufacturers have so far responded to professionals' concerns, and details the most recent studies of the safety of stents. Written by Miriam Shuchman, an assistant professor at the School of Medicine and Biomedical Sciences at the University of Buffalo, it concludes that the damage to the “golden reputation” of drug eluting stents had already led to a small but measurable fall in the sales of these devices, whereas sales of their conventional predecessors, bare metal stents, have increased.

The immediate future of drug eluting stents will be determined by a meeting of the FDA's circulatory system devices advisory panel, which is due to be held in early December. One option the panel will consider is extending the time that patients take antiplatelet treatment after being given a stent, the article says.

The stent issue first became public on a major scale in September at the Barcelona World Congress of Cardiology (BMJ 2006;333:569, 16 Sep). The two leading manufacturers, Boston Scientific and Johnson & Johnson, have since suspended their rivalry to cooperate in a meta-analysis of their data. This analysis confirmed an increased risk of thrombosis in patients with drug eluting stents that have been in place for at least one year.

The medical statistician Stuart Pocock of the London School of Hygiene and Tropical Medicine, an authority on cardiovascular trials, has acted as an adviser to the FDA on some of the findings of the stent research. Although he accepts that recent revelations have caused an upset, he said that the future outlook for the devices will probably not be radically changed. He said, “The harm needs to be set against the superior efficacy of these stents in preventing recurrence [of vessel closure].”

The short term benefit of drug eluting stents over bare metal devices is not in dispute: they offer a significantly lower rate of restenosis. The problem emerges in the long term and in particular after the course of antiplatelet treatment that is routinely prescribed after their implantation is finished.

One remedy may be to extend the period of antiplatelet treatment or even to continue it indefinitely. “This is slightly open to debate,” Professor Pocock said. “One anticipates it would deal with the problem, but we don't have good data to prove that.” Existing studies may cast some light—but not conclusively, as the emergence of the thrombosis problem had not been anticipated when the stents were designed.

On differences between countries in the use of drug eluting stents, Professor Pocock said, “Some other countries, particularly the US, intervene more often in asymptomatic patients. In the UK we tend to wait until patients have symptomatic disease. So it's not just a blanket question of whether these stents are safe or not, but who you give them to. If you intervene in symptomatic patients where the benefits to their quality of life are clear, the risks may become more justifiable.”