This is the VOA Special English Health Report.

A coronary stent is a small tube that is used to treat heart patients. The tube is made of

wire mesh. Doctors place it inside an artery that has narrowed. They expand the stent to hold the walls of the artery open so blood can flow normally to the heart. If an artery is blocked, people can suffer chest pain and heart attacks.

In most cases, a stent is left permanently in place to keep the artery open after a treatment called angioplasty.

Increasingly doctors use what is called a drug-eluting stent. This kind has medicine on it that is released slowly over time. The drug is designed to prevent the creation of scar tissue in the artery. Scar tissue can cause the artery to narrow again.

Millions of people now have drug-eluting stents. The United States Food and Drug Administration approved the first one in two thousand three. The devices are approved for use in patients with simple blockages and no history of a heart attack.

But once the F.D.A. approves a drug or other treatment, doctors do not have to follow only the approved uses. They may try other uses, including untested uses, if they think it could help their patients. This is called "off-label" use.

But recently some studies have questioned the safety of off-label use of drug-treated stents.

In early May, the Journal of the American Medical Association published two studies. These were based on the records of several thousand patients.

A stent maker, Cordis, helped pay for one of the studies. The study found that at one year, the patients with the least risk were those who met the conditions for approved or "on-label" use.

For example, restenosis, which is when the artery narrows again, was reported in four percent of those patients. Patients with more serious artery problems had rates of seven to eight percent. Still, the researchers say the number of patients affected was small.

Compared to the first study, the second study found a higher risk of problems with off-label use of drug-eluting stents. Millenium Pharmaceuticals and Schering-Plough helped pay for the second study. These companies make drugs that can be used in place of the stents.

Now, additional research is examining how outcomes could be affected by the methods that doctors use when they put a stent into a patient. We will discuss this part of the issue next week.

And that's the VOA Special English Health Report, written by Caty Weaver. I'm Katherine Cole.