After two years, a study examining devices that measure pressure around heart-artery blockages to help place stent scaffolds showed using the devices cut the odds of death or heart attacks compared with a traditional imaging tool.

St. Jude Medical Inc. (STJ) and Volcano Corp. (VOLC) make these fractional flow reserve, or FFR, measurement tools, which involve a wire with a pressure sensor that determines the significance of narrowing in heart arteries. The devices could lead to more selective use of heart stents, where Abbott Laboratories (ABT), Boston Scientific Corp. (BSX), Johnson & Johnson (JNJ) and Medtronic Inc. (MDT) are major manufacturers.

Two-year results from the St. Jude-sponsored "Fame" study were released Wednesday at the Transcatheter Cardiovascular Therapeutics conference in San Francisco.

One-year results that also backed the technology were released at the same conference last October, and later published in the New England Journal of Medicine. St. Jude bought Radi Medical Systems, a Swedish company that makes FFR tools, for $250 million in cash not long after Fame's one-year data were issued.

The study included 1,005 patients with problems in multiple heart arteries. Their treatment was either guided with FFR or just an angiogram imaging system.

After two years, there was an 8.4% risk of patients dying or having a heart attack when treatment was guided with FFR, compared with a 12.7% rate among patents whose treatment was guided with an angiogram.

While the rates of these serious complications was lower for the FFR group, about a third-fewer stents were used among those patients compared with patients in the angiogram group. That doesn't mean FFR technology kept many patients from getting stents - 90% of the patients in that group still got them - but it did help determine how many stents they received.

"We're not saying stenting is bad," said William Fearon, associate director of interventional cardiology at Stanford University Medical Center and the co-principal investigator on the Fame study. But the message is there is a more efficient and effective way to do stenting procedures, he said in an interview.

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