WEDNESDAY, Aug. 31, 2016 (HealthDay News) -- The largest trial ever conducted on stents -- tiny tubes that help keep heart arteries open -- suggests that pricey drug-coated (or eluting) versions may perform no better for patients over the long-term, in terms of patient survival, compared to cheaper, "bare metal" versions.

"The evidence in favor of contemporary drug-eluting stents over bare-metal stents may not be as strong as has been thought," said study author Dr. Kaare Harald Bonaa. He's from the Norwegian University of Science and Technology in Trondheim, Norway.

Bare-metal stents were used in the early days of stenting. But, arteries sometimes re-closed around the stent. That meant surgeons often had to go back in and re-open the vessel -- a procedure called revascularization.

Then came drug-eluting stents. These devices were coated with drugs to prevent the vessel re-closure that plagued so many patients. These newer stents quickly became popular with doctors, but at prices that were often thousands of dollars more than bare-metal versions, according to previous research.

The new study sought to revisit the issue of bare-metal versus drug-eluting stents, and is the largest of its kind to date, Bonaa said. His team tracked six-year outcomes for more than 9,000 patients. Patients received a stent after suffering recurrent chest pain (angina) or an event such as a heart attack.

Patients who received a drug-eluting stent typically received devices coated with anti-clotting drugs that are still in frequent use today, Bonaa said.

The study found no significant difference between drug-eluting or bare-metal stents in either total patient deaths, nonfatal heart attacks, angina or even patient quality of life.

Patients who received a drug-eluting stent did, as expected, have less need for a second revascularization procedure, but not to the level surgeons might have expected, Bonaa said.

In fact, "thirty patients would need to be treated with drug-eluting stents rather than with bare-metal stents to prevent one repeat revascularization," he said.

Overall rates of revascularization procedures were low in each group, he noted: 16.5 percent in the drug-eluting stent group versus 20 percent in the bare-metal stent group.

Overall, "the take home message is that patients treated with drug-eluting stents do not live longer nor better than patients treated with bare-metal stents," Bonaa said.

Given the added cost of drug-eluting stents, does it make sense to choose them in most cases? Bonaa said the jury is still out on that.

"We have not yet determined at present how our findings may change current practice," he said.

"It is true that drug-eluting stents are more expensive that bare-metal stents, but that may be offset by the cost of added revascularization procedures required for patients with bare-metal versions," he added.

Cardiologists expressed caution in over-interpreting the new study results.

Dr. Andreas Baumbach is professor of interventional cardiology at the University of Bristol in the United Kingdom. He said that because drug-eluting stents help prevent artery re-closure, they are still the best choice for many patients.

The new trial "really doesn't say at all that there's a group of patients that don't need a drug-eluting stent," he said.

In Baumbach's view, "What the trial says is that it's not a crime to put a bare-metal stent in, the results are good, particularly with the new-generations of bare-metal stents. The results (with bare-metal stents) are OK, but still the drug-eluting stents do better."

Bonaa presented the findings Tuesday in Rome at the annual meeting of the European Society of Cardiology. The findings are also being published simultaneously in the New England Journal of Medicine.

More information

To learn more about stents, visit the U.S. National Heart, Lung, and Blood Institute.