Drug-Coated Stents Help Diabetics with Heart Repair

Diabetic patients who received drug-eluting stents had significantly less renarrowing of their treated arteries and fewer serious cardiac problems than those treated with standard stents, which do not release a drug, according to a report in the medical journal Circulation.

Stents are small mesh tubes that help keep arteries open after angioplasty.

Drug-eluting stents are coated with medication to prevent the formation of scar tissue inside the stent. These drug-eluting stents release medication within the blood vessel itself. This medication inhibits the overgrowth of tissue that can occur within the stent. The effect of this medication is to deter the narrowing of the newly stented blood vessel.

Diabetics Have High Risk

According to the study, diabetes afflicts more than 150 million people worldwide and is a major risk factor for heart disease and stroke, which progresses faster in diabetic patients than in nondiabetics.

Among patients with diabetes, cardiovascular disease is responsible for 75 percent of all hospital admissions and at least 80 percent of deaths, researchers say.

The finding is no great surprise, since a number of studies in the US and other countries have shown the advantage of drug-eluting stents.

But the result is important because "overall, the outcomes of diabetic patients after angioplasty are poorer than those of nondiabetics," says study author Dr. Manel Sabate, a consultant in cardiology at San Carlos University Hospital in Madrid.

The study included 160 people with diabetes, half of whom had bare metal stents inserted after angioplasty. The other half got stents coated with the drug sirolimus. Sirolimus prevents further narrowing by inhibiting scar tissue formation.

In the nine months following the procedure, arteries of patients given drug-coated stents narrowed by an average of only 0.06 millimeters, compared to 0.47 millimeters for the arteries of those given bare-metal stents, the researchers report.

That difference had a very practical benefit.

While 29 of the 80 patients who got the bare metal stents died or had adverse cardiac events such as heart attacks, only eight of the 80 who got coated stents had such outcomes.

Only five of those who got coated stents needed repeat angioplasty, compared to 25 of those getting the bare metal stents.

During hospitalization, three standard-stent patients suffered heart attacks, and one died of a cardiac rupture. There were no major cardiac events in the drug-stent group.

"Conventional stent implantation still exhibits a high incidence of major cardiac events in the diabetic population, especially in those requiring insulin," Sabate said. "With the use of conventional stents, the expected re-narrowing rate may vary from 30 percent to 60 percent in diabetic patients vs. 15 percent to 30 percent in nondiabetic patients."

The researchers said they will continue to monitor the patients for the next two years to evaluate the long-term value of drug-eluting stents.

Studies Find Improvement

Sirolimus, the drug used in the Spanish study, is one of two medications available to coat stents.

Two European studies recently found an advantage of sirolimus over the other drug, paclitaxel. The benefit in terms of keeping arteries open, preventing heart attacks, and keeping patients alive was greatest for people at highest risk - a group that includes diabetics.

"It's an important study because it was specifically designed to look at stents in patients with diabetes, rather than drawing on a subgroup in a larger trial," says Dr. Sidney Smith, a professor of medicine at the University of North Carolina and a spokesman for the American Heart Association.

The study is "good news for patients with diabetes," Dr. Smith explains. "It shows that sirolimus-coated stents improve treatment in both insulin-treated and noninsulin-treated diabetics."

The only flaw of the clinical trial was that it began before the latest generation of stents became available, he notes.

"The trial did not compare the newer cobalt chromium stents," Dr. Smith says. "It will be important to evaluate them."

Always consult your physician for more information.