A big study analyzing outcomes for patients with both regular heart stents and versions coated with medication found patients with the coated devices had fewer cases of serious complications.

The data, which covered nearly 263,000 patients treated over three years, were released Saturday at the American College of Cardiology's annual conference.

The study lends support to a $4 billion drug-coated stent business that has been steadily working its way back from worries about safety problems. Boston Scientific Corp. (BSX), Abbott Laboratories (ABT), Johnson & Johnson (JNJ) and Medtronic Inc. (MDT) are the big stent makers.

Coronary stents are tiny devices used to prop open clogged heart arteries. Older, bare-metal ones can be susceptible to scar tissue that narrows arteries and sometimes leads to another procedure, while coated stents use medication to fight this process. They have proven successful at that task, but worries arose a few years ago that coated stents were also more likely to trigger potentially deadly clots.

The connected worry that clots meant coated-stent patients were more likely to die triggered a major drop in coated-stent usage. The market hasn't bounced all the way back, but has been steadily recovering amid data indicating this isn't the case.

The new study, which involved analysis of a major data registry, furthered that trend by not showing safety issues with coated devices over 30 months.

"We can say with some confidence that they're not killing people," said Pamela Douglas, a professor of medicine at Duke University who presented the study data Saturday, during a press conference.

While some coated stents may have a slight inclination to allow clots, patients now take longer and sometimes open-ended courses of anti-clotting drugs, and doctors will steer patients who can't take such medication to bare-metal stents.

The latest study - the largest-ever to evaluate real-world stent patients - involved analysis of data from ACC's National Cardiovascular Data Registry on patients over the age of 65. It included 217,675 patients with coated stents and 45,025 with bare-metal devices.

The study found that patients with coated stents had significantly lower rates of death and non-fatal heart attacks. There were slightly fewer cases of repeat procedures with coated stent patients and stroke rates were similar in both groups, according to slides from Douglas' presentation.

This study wasn't a randomized and controlled trial reviewing the two types of stents, which means it doesn't have the highest possible level of evidence. But randomized trials often include more basic cases, while this study reviews the kinds of patients doctors are more likely to see on a day-to-day basis.

The study was funded by the Cardiovascular Consortium of the Agency for Healthcare Research and Quality, which is part of the U.S. Department of Health and Human Services. ACC's registry also provided support.

-By Jon Kamp, Dow Jones Newswires; 617-654-6728; jon.kamp@dowjones.com