A study funded by Medtronic Inc. (MDT) showed that training aimed at getting doctors to stick to guidelines for treating chronic heart-failure patients increased usage of expensive, implantable devices, the company said Monday.

This is a goal for Medtronic, which leads a $6 billion market for defibrillators that grew rapidly earlier this decade, but has settled into a modest growth pattern in recent years amid fallout from device recalls. Manufacturers have been frustrated by the fact that many patients who are candidates for defibrillators still never get a device that typically costs $25,000 or so depending on the features.

Two-year results from the 35,000-patient "Improve HF" study, which involved 167 U.S. cardiology practices, suggested the low-utilization issue can be partially overcome through training programs and other educational materials that reinforce guidelines for treating heart problems.

These efforts also helped increase usage of heart-failure drugs and improved patient education regarding their symptoms, Medtronic said. There was no improvement, however, when it came to usage of blood thinners to combat a common rhythm problem that can boost the risk of strokes.

Two-year results from Improve HF were announced Monday at the Heart Failure Society of America's annual conference in Boston.

Most relevant for Medtronic are study details involving two types of implanted devices. Cardiac resynchronization therapy, or CRT, devices constantly coordinate beating in erratic hearts and often have defibrillators on board to provide shocks when needed to combat potentially deadly problems. The study also included implantable cardioverter defibrillators, or ICDs, which are often idle unless shocks are needed.

Baseline data unveiled two years ago, before any performance improvement intervention at participating facilities, showed only 38% of eligible patients received CRT devices. But after two years, utilization improved to 69%, Medtronic said.

For ICDs, roughly half of eligible patients got one before the intervention efforts, but the number improved to 79% after two years.

The challenge for Medtronic is to see whether these results can be replicated outside the study, where a slowly expanding defibrillator market has in recent years confounded hopes for more rapid growth based on the large pool of prospective patients. Device recalls - including Medtronic's recall two years ago of faulty cables that connect defibrillators to the heart - have not helped.

How the findings are more broadly applied remains to be seen. Medtronic can provide resources for the type of training used in the study, but wants to review such ideas with leading heart-failure experts, said Marshall Stanton, vice president of clinical research for Medtronic's heart-rhythm business.

The Improve HF results "can be replicated in other centers," Stanton said in an interview.

Shares of Medtronic recently traded up 59 cents, or 1.6%, to $38.49. Medtronic competes in the market for implantable heart-rhythm devices with Boston Scientific Corp. (BSX) and St. Jude Medical Inc. (STJ).

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