Aug. 11, 2004 -- A new study shows that drug-coated stents designed to prevent repeat blockage of heart arteries apparently do just that. But Canadian researchers say there is no evidence that they actually prevent heart attack or death.
Stents are small, wire-mesh tubes placed in a heart artery after balloon angioplasty, a procedure to reopen the artery when it's blocked or narrowed. Stents act like scaffolds, widening the artery to increase the flow of blood to the heart.
There are two different kinds of available stents. Some are made of bare metal; others, called drug-eluting stents, have a polymer coating that releases drugs designed to prevent repeat blockage of the artery. One of the problems seen with bare stents was growth of cells around the stents that caused the blood vessel to narrow again.
Which Stent Is Better?
Mark Eisenberg, MD, of Jewish General Hospital at McGill University in Montreal led a review of 11 past stent studies including a combined total of more than 5,000 people. His study appears in the Aug. 14 issue of The Lancet.
The patients who got drug-eluting stents had half the rate of severe heart events as those who had bare-metal stents (8% vs. 16%).
Nearly 20% more people had narrowing of their coronary artery six to 12 months after receiving bare-metal stents compared with those with drug-eluting stents.
The benefits of drug-eluting stents appear to stop there. People with drug-eluting and bare-metal stents had the same risk of death or heart attack.
The study, which shows drug-eluting stents to be safe, had a short- to medium-term outlook. Eisenberg and his colleagues call for "larger studies with longer follow-up" to shed more light on drug-eluting stents.
German researchers Joachim Schofer and Michael Schlüter agree in a commentary also published in The Lancet. They are with the Centre for Cardiology and Vascular Intervention in Hamburg, Germany.
For instance, Schofer and Schlüter ask if the drug-eluting stents will have adverse effects after releasing the drugs, and whether the drug-eluting stents just delay a renarrowing of the coronary artery, rather than preventing it.