Drug-coated heart stents carry higher risk: study

NEW ORLEANS (Reuters) - Drug-coated stents carried a small but significantly greater risk of blood clots and heart attacks, compared to older bare-metal versions of the medical devices, a study released on Saturday found.

The study, which also concluded that the stents' benefits outweigh this risk, found blood clot and heart attack risks were greater between 12 months and 15 months after implantation for patients with the medical devices, used to prop open surgically cleared arteries.

"Even in a short three-month period, you saw a trend," toward increased blood clotting, said Spencer King, head of interventional cardiology at Atlanta Piedmont Hospital.

Results add to a growing debate over the popular drug-coated stents, which are better at preventing the re-narrowing of arteries that may eventually occur in some patients getting an older, bare-metal variety.

Data revealing the formation of blood clots long after implantation has cast a cloud over the devices' safety.

Total mortality was similar in both groups, though those with drug-coated stents had a 43 percent reduction in repeat procedures.

Drug-coated versions of the mesh tubes quickly usurped an older, bare-metal type when introduced three years ago. The newer, more pricey versions were seen as a medical breakthrough and created a $6 billion market for stent-makers Johnson & Johnson and Boston Scientific.

The study, of 12,400 patients in Denmark who were randomly given bare metal or drug-coated stents, found rates of blood clots and heart attacks were similar over 15 months. However, over the last three months of that period, an increased risk of blood clotting and heart attack was seen with drug-coated stents.

Study author Michael Maeng of Aarhus University Hospital in Denmark said further study is needed to determine if "the very small excess of stent thrombosis (blood clotting) and heart attack in the 12 to 15 month time period will continue to increase."

"The follow-up may still be insufficient to completely quantify possible risks" of blood clotting, he added.

He also said the increased risk of clotting was so small that it did not outweigh the device's benefits, including the need for fewer new procedures.

Because of concerns over blood clots, the drug-coated variety makes up about 70 percent of the stent market, down from 95 percent about a year ago.